\definecolor{green}{cmyk}{0,0.25,0.5,0}
\definecolor{orange}{cmyk}{0,0.25,0.5,0}

\newcommand{\weblong}[2]{\href{#1}{#2}} % definition of long hyperreferences
\newcommand {\excl}[1]{
  \begin{tabular}{r p{0.75\textwidth}}
    \hspace*{5mm}\LARGE{\textcolor{green}{$!$
      %\ArrowBoldDownRight
    }} & #1\\
  \end{tabular}
}
\newcommand {\photo}[3]
{
  \begin{center}
  \includegraphics[width=0.5\textwidth]{img/#3}
  \end{center}
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\IfLanguageName{french}{
  \chapter{Un tutoriel de base de simulation de vol}
}{
  % default: English
  \translatorStart
  \chapter{A Basic Flight Simulator Tutorial}
  \translatorEnd
}
\label{basic}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\IfLanguageName{french}{
  \section{Pr\'{e}ambule}
}{
  % default: English
  \translatorStart
  \section{Foreword}
  \translatorEnd
}
\label{sec:Foreword}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\IfLanguageName{french}{
  L'aviation est faite d'extr\^{e}mes :

  \begin{itemize}
    \item Un a\'{e}ronef est assez fragile et vole \`{a} des vitesses \'{e}lev\'{e}es.
          Cependant, c'est l'un des moyens de transports les plus s\^{u}rs.
    \item Les pilotes doivent constamment suivre des r\`{e}gles et des proc\'{e}dures.
          Cependant, un a\'{e}ronef est un symbole de libert\'{e}.
    \item Avec un peu d'entra\^{\i}nement, voler un petit a\'{e}ronef est simple.
          Cependant, si un probl\`{e}me survient, vous devez \^{e}tre capable de le r\'{e}soudre en quelques secondes.
    \item De nombreux tutoriels de vols sont \'{e}crits avec beaucoup d'humour.
          Cepedant, ne pas prendre le vol au s\'{e}rieux vous rem\`{e}nera sur le plancher des vaches de mani\`{e}re pr\'{e}matur\'{e}e.
  \end{itemize}
}{
  % default: English
  \translatorStart
  Aviation is about extremes:

  \begin{itemize}
    \item An airplane is quite fragile and flies at high speeds.
          Yet it is one of the safest forms of transport.
    \item Pilots must constantly follow rules and procedures.
          Yet an airplane is a symbol of freedom.
    \item With a little bit of training, flying a small aircraft becomes easy.
          Yet if a problem occurs, you must be able to resolve it within a few seconds.
    \item Many flight tutorials are written with a lot of humor.
          Yet not taking flying seriously will bring you down to earth prematurely.
  \end{itemize}
  \translatorEnd
}

\IfLanguageName{french}{
  L'a\'{e}ronef utilis\'{e} dans ce tutoriel est le
  \weblong{http://en.wikipedia.org/wiki/Cessna_172} {Cessna 172P}. Il s'agit de l'avion
  utilis\'{e} dans de nombreuses v\'{e}ritables \'{e}coles de pilotage et c'est un avions tr\`{e}s agr\'{e}able en vol.
}{
  % default: English
  \translatorStart
  The aircraft used in this tutorial is the \weblong{http://en.wikipedia.org/wiki/Cessna_172} {Cessna 172P}.
  This is the aircraft used in many real life flight schools and it is a great airplane to fly.
  \translatorEnd
}
\medskip

\centerline{
  \includegraphics[width=\textwidth]{img/basic_tutorial/sight-seeing}
}
\newpage

\IfLanguageName{french}{
  Les articles suivants compl\`{e}tent ce tutoriel et r\'{e}pondront \`{a} la plupart des questions qui pourraient
  survenir lors de votre lecture. Le premier, en particulier, est une bonne
  introduction aux principaux composants et contr\^{o}les de l'a\'{e}ronef :
}{
  % default: English
  \translatorStart
  The following articles complement this tutorial and will answer most questions that may arise as you read through.
  The first one in particular is a good introduction to the airplane's main components and controls:
  \translatorEnd
}

\begin{itemize}
    \item \weblong{https://www.gleim.com/aviation/learn-to-fly/}    {https://www.gleim.com/aviation/learn-to-fly/}
    \item \weblong{http://www.pilotfriend.com/training/flight\_training/aero/principa.htm}    {http://www.pilotfriend.com/training/flight\_training/aero/principa.htm}
    \item \web{http://en.wikipedia.org/wiki/Aircraft}
    \item \web{https://en.wikipedia.org/wiki/Flight\_control\_surfaces}
    \item \web{http://en.wikipedia.org/wiki/Airplane\_flight\_mechanics}
    \item \web{http://en.wikipedia.org/wiki/Aircraft\_engine\_controls}
    \item \web{http://www.navfltsm.addr.com/}
    \item \web{http://www.free-online-private-pilot-ground-school.com/}
\end{itemize}

\IfLanguageName{french}{
  Ce tutoriel est pr\'{e}cis dans les limites de mes meilleures connaissances, mais il contiendra in\'{e}vitablement
  quelques erreurs. Je m'excuse par avance pour celles-ci.
}{
  % default: English
  \translatorStart
  This tutorial is accurate to the best of my knowledge, but will inevitably contain some mistakes.
  I apologize in advance for these.
  \translatorEnd
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\IfLanguageName{french}{
  \section{D\'{e}marrer}
}{
  % default: English
  \translatorStart
  \section{Starting Up}
  \translatorEnd
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\IfLanguageName{french}{
  Il existe diff\'{e}rentes mani\`{e}res de d\'{e}marrer \FlightGear{} en fonction de la
  plate-forme et de la distribution que vous utilisez.
}{
  % default: English
  \translatorStart
  There are a number of different ways to start \FlightGear{} based on your platform and the distribution you are using.
  I will refer you back to Chapter~\ref{takeoff},~\nameref{takeoff}.
  \translatorEnd
}
\newpage
\subsection{Using the Launcher}
\IfLanguageName{french}{
  Sur MS Windows, \FlightGear{} dispose d'un assistant en mode graphique dans
  lequel vous pouvez choisir votre a\'{e}ronef et votre position de d\'{e}marrage.
  Choisissez d'abord l'a\'{e}ronef Cessna 172p comme montr\'{e} ci-dessous.
  Pour correspondre \`{a} ce tutoriel, ne choisissez pas la version avec panneau 2D.
  (Vous pourriez cependant trouver dans le futur que la version 2D est plus
  appropri\'{e}e pour l'entra\^{\i}nement. Cliquez sur le bouton \button{Suivant}
  pour choisir votre a\'{e}roport.
}{
  % default: English
  \translatorStart
  \FlightGear{} has a Launcher in which you can choose your aircraft and starting postion.
  From along the left edge, select the \command{Aircraft} tab and then choose the \command{Cessna 172P Skyhawk} airplane as shown below.
  To match this tutorial do not choose the 2D panel version.
  (You may however find in the future that the 2D version is more appropriate for training.)
  Click the \button{Back} button if you need to choose a different aircraft.
  \translatorEnd
}
\medskip

\centerline{
  \includegraphics[clip,width=12.5cm]{img/basic_tutorial/launcher-1}
}
\medskip

\IfLanguageName{french}{
  Vous pouvez d\'{e}marrer de n'importe quel a\'{e}roport pour ce tutoriel, mais je partirai
  du principe que vous d\'{e}marrerez de l'a\'{e}roport de San Francisco (KSFO), l'a\'{e}roport
  par d\'{e}faut de FlightGear :
}{
  % default: English
  \translatorStart
  You can start from any airport for this tutorial, but I will assume that you will start from FlightGear's default airport of
  Honolulu International (PHNL):
  \translatorEnd
}
\medskip

\centerline{
  \includegraphics[clip,width=12.5cm]{img/basic_tutorial/launcher-2}
}
\newpage

\IfLanguageName{french}{
  une fois que vous avez choisi KSFO et cliqu\'{e} sur le bouton \button{Suivant}, vous pourrez
  param\'{e}trer toutes les options que vous souhaitez pour le simulateur.
  Pour votre premier vol, je vous sugg\`{e}re de d\'{e}marrer \`{a} l'heure
  de midi.
}{
  % default: English
  \translatorStart
  From the Location tab, once you have selected PHNL (clicked on the \button{Back} button if you need to change it),
  you can then set any number of options for the simulator.
  For your first flight, I suggest setting the \command{Time of day} to \command{Noon} within the Environment tab.
  \translatorEnd
}
\medskip

\centerline{
  \includegraphics[clip,width=12.5cm]{img/basic_tutorial/launcher-3}
}
\medskip

\IfLanguageName{french}{
  Je recommanderais \'{e}galement de d\'{e}buter avec une petite
  r\'{e}solution de $800\times600$. Par la suite, vous pourrez vous amuser avec les
  options et utiliser une meilleure r\'{e}solution, cependant ceci affecte la performance de
  mani\`{e}re n\'{e}gative. Cliquez sur le bouton \button{D\'{e}marrer} et \FlightGear{} d\'{e}marrera avec les options que vous avez
  choisi.
}{
  % default: English
  \translatorStart
  I also recommend that you start with a small resolution of $800\times600$.
  You can change the resolution via the \command{Settings} tab and click \button{Show more} in section \command{View and Window}.
  Later on, you can play around with the options and use a higher resolution, but this obviously adversly affects performance.
  Click on the \button{Fly!} tab and \FlightGear{} will start with the options you have selected.
  \translatorEnd
}
\medskip

\centerline{
  \includegraphics[clip,width=12.5cm]{img/basic_tutorial/launcher-4}
}
\medskip

\IfLanguageName{french}{
  Si vous rencontrez des difficult\'{e}s \`{a} faire fonctionner la derni\`{e}re version de
  \FlightGear{} sur votre syst\`{e}me Windows, vous pourriez tender d'essayer une version
  avec des pr\'{e}-requis moindres en mati\`{e}re de graphisme (comme par exemple la
  0.9.8). Vous pouvez trouver les version pr\'{e}c\'{e}dentes sur les miroirs FTP
  mentionn\'{e}s en haut de la page de t\'{e}l\'{e}chargement de \FlightGear{} :
  \weblong{http://www.flightgear.org/download/}.
}{
  % default: English
  \translatorStart
  If you have problems running the latest version \FlightGear{} on your system, you may want to try an earlier version with lower
  graphics requirements.
  You can find previous releases on the FTP mirrors mentioned at the top of the \FlightGear{} download page:
  \web{http://www.flightgear.org/download/}.
  \translatorEnd
}
\newpage

% default: English
\translatorStart
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{The First Challenge - Flying Straight}
\label{sec:FlyingStraight}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Once \FlightGear{} is started you will see the scene shown below.
Your first task is to get the engine running, which is most easily performed via the menu bar \command{Cessna C172P -> Autostart}. 
\medskip

\centerline{
  \includegraphics[clip,width=15.0cm]{img/basic_tutorial/autostart}
}
\medskip

The aircraft is at the start of the runway with the engine running at low power.
With the prop now spinning, the airplane may occasionally tremble a little, but it should not move.
\medskip

\centerline{
  \includegraphics[clip,width=15.0cm]{img/basic_tutorial/on-runway}
}
\medskip

\subsection*{About the keyboard.}\index{keyboard}

\begin{itemize}
  \item In this tutorial, a lowercase letter key indicates you should simply press that key.
        An uppercase means you must press shift and that key.
        (The \textcolor{blue}{\key{$\Uparrow$~Shift}} keys are those two keys with a hollow fat arrow pointing upwards.)
        In other words: if you are told to type ``v'', simply hit the \key{v} key briefly.
        \index{keyboard!uppercase and lowercase keys}
        If you are told to type ``V'', press the \key{Shift} key down and while you have it pushed down, hit the \key{v} key,
        then release the \key{Shift} key.
        (In short: V is the same as \key{Shift-v}.)
	\item The tutorial will assume you have the \key{NumLock} on.
        \index{keyboard!numeric}
        When switched on, you should find a small green light on at the right of your keyboard.
        Press the \textcolor{green}{\key{NumLock}} key repeatedly until the lamp is on.
\end{itemize}
\medskip

\centerline{
  \includegraphics[width=0.95\textwidth]{img/basic_tutorial/numlock}
}
\medskip

\index{view!changing}
Press \key{v}, to view the aircraft from the outside.
Type \key{v} repeatedly to cycle through a number of different available views until you return to the cockpit.
Pressing \key{V} will cycle backwards through the views.
\key{Ctrl-v} will return you directly back to the cockpit view:
\medskip

\centerline{
  \includegraphics[clip,width=7.0cm,height=4.0cm]{img/basic_tutorial/extern1}
  \includegraphics[clip,width=7.0cm,height=4.0cm]{img/basic_tutorial/extern2}
}
\medskip

In real life, we would have inspected all around the plane to check that everything is working, to confirm that nothing is
hampering the moving parts, and that nothing is obstructing the instrument openings.
In the simulator, this is already done for us before we start.

Hold the \key{PageUp} (numPad-9) key down for about eight seconds.
You will hear the engine sound rise as the throttle is advanced to full power.

The airplane will start accelerating down the runway.
As it does so, it will drift to the left, before finally taking off, banking to the left, falling to the ground and crashing (probably).

\index{view!instant replay}
You can see a replay of the crash using the \command{View -> Instant Replay} menu.
Click the \button{Replay} button at the bottom of the dialog window, then use \key{v} and \key{V} to see the airplane from the outside.
The picture below shows the end part of the flight.
You can take a snapshot by typing the \key{F3} key.
You can also use the \key{F10} key to toggle the menu bar on or off.
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/crash}
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/crash-plunged-to-ground}
}
\medskip

Having observed your crash, reset \FlightGear{} using \command{File -> Reset}, to return to the pre-crash condition.

In order to fly straight we will need to take advantage of the the airplane's control\index{yoke} yoke:
\medskip

\centerline{
  \includegraphics[width=\textwidth]{img/basic_tutorial/yoke}
}
\medskip

You can control the yoke using a joystick, or by moving the mouse.
To use the mouse you need to be in mouse yoke mode.
Get into that mode by pressing \key{Tab}.
The mouse cursor becomes a $+$ symbol.
Move the mouse and see the yoke moving accordingly.
Type \key{v} to see the plane from the outside.
If you move the mouse again you will see movement of the rudder, elevator (tail) and the ailerons (wings).
If your viewpoint is too far from the aircraft to see any movement, type \key{x} a few times to zoom in.
Type \key{X} to zoom back out.
\key{Ctrl-x} returns the view to the default zoom level.
Use \key{Ctrl-v} to change the view back into the cockpit.

Pressing \key{Tab} again gets you into mouse view mode.
In this mode the mouse cursor will be a $\leftrightarrow$ symbol.
This allows you to look around easily by moving the mouse.
Clicking the left mouse button will re-center the view.
You can also change your view direction in the normal and yoke modes by holding down the right mouse button and moving the mouse.
A further press of \key{Tab} will return you to the normal mouse mode.

To summarize, the \key{Tab} key cycles the mouse through three modes:
\begin{itemize}
  \item \textit{Normal mode}\index{mouse!normal mode}.
        This mode allows you to click on the menu and on the instrument panel.
  \item \textit{Yoke mode}\index{mouse!yoke mode}\index{yoke!mouse yoke mode}.
	      The mouse controls the yoke (+ pointer).
  \item \textit{View mode}\index{mouse!view mode}.
        The mouse controls the view direction ($\leftrightarrow$ pointer).
\end{itemize}

Try taking off again using the mouse to control the yoke.
Press \key{Tab} to put the mouse in yoke mode ($+$ pointer) and raise the engine throttle to maximum by holding the \key{PageUp} key down.
Do not try too hard to keep the airplane rolling straight on the runway using the mouse / yoke.
It is okay to let it drift a bit leftwards.
Wait until it rises into the air.
Then use the mouse to try and get the airplane to fly straight.
(If you want to control the airplane on the ground see section \ref{sec:TaxiTurning}.)

You will find that you must prevent the airplane from banking to the left\ldots or to the right:
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/bank-left}
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/bank-right}
}
\medskip

... or from plunging toward the ground:
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/crash}
}
\medskip

Try to fly, more or less straight, with the horizon line slightly above the airplane nose:
\medskip

\centerline{
  \includegraphics[width=\textwidth]{img/basic_tutorial/straight-level}
}
\medskip

Whatever your skills at video games or simpler simulators, you will probably not succeed at first.
The airplane will crash, probably quite soon after take-off.
This is the moment where it is common for the novice pilot to begin to despair and abandon trying to fly a simulator or a real aircraft.
Just hold tight and keep trying.
Eventually you will develop a feel for the subtle control inputs required.
\medskip

\subsection*{Common Mistakes}\index{CommonMistakes}

\index{yoke!pulling}
The most common errors are moving the controls too much, which lead to the aircraft getting out of your control,
or moving the mouse forward in an attempt to bring the nose up.
\medskip

You will learn that small yoke movements have a fairly large effect on the aircraft's reaction.
Go easy on the controls by using small yoke movement.
You may always add a touch more control input if you see the aircraft is responding too subtly.
Inversely, too much yoke movement can cause a severe response from the aircraft and then you find yourself in a
poor situation as you desperately attempt to regain control. 
If over-control is especially difficult for you, then you may find that decreasing your mouse sensitivity could help
during your initial training.
\index{troubles!mouse speed}

Remember, \command{pull} the nose up and \command{push} the nose down.
You must pull the yoke aft, by moving the mouse backwards, to raise the nose.
Equally, when you want to lower the airplane's nose, you must move the mouse forwards.
This can seem odd, but all airplane control yokes are designed that way.
With time, you will wonder how you every thought it worked any other way.

If you have difficulty visualising this, the following analogy may help.
Imagine a soccer ball is on your desk and you have ``glued'' your hand to the top of it.
If you move your hand forward the ball will roll forward and your fingers will point toward the desk.
If you move your hand backward the ball will roll backward and your fingers will now point up at the ceiling.
Your hand is the airplane.
\medskip

Another common mistake is the assumption that the control inputs directly match airplane bank.
In other words, you believe if the control yoke is level, the airplane will fly level.
This is not true.
The yoke controls the \emph{rate} at which the airplane banks.
If the airplane is banked 20\textdegree{} to the left and the control yoke is level, the airplane will stay banked at
20\textdegree{} left until some other force affects it.
If you want to return the airplane to level flight, you have to turn the control yoke slightly to the right
(move the mouse slightly rightwards) and keep it slightly to the right for a while.
The airplane will turn slowly rightwards.
Once it is level with the horizon, bring the control yoke level too.
Then the airplane will stay level (until some other force changes its orientation).
\medskip

A third error is trying to find ``the right position'' for the yoke / mouse.
Naturally, you will want to find the fine tuning that will leave the airplane fly straight.
Actually there is no such ideal yoke position.
The airplane is inherintely unstable in the air.
You must constantly correct the airplane's attitude and keep it flying straight with tiny movements of the mouse.
This may seem to take all your concentration intially, but just like driving a car,
keeping the aircraft straight and level will soon become second nature.
For longer flights, you will eventually use the autopilot to keep the airplane level, but this is outside the scope of this tutorial.

To help fine-tune your senses to the control inputs required, keep your eyes on the outside scenery and not get fixated on the
instruments or the yoke.
Check the angle of the horizon and its height above the airplane's nose.
The horizon line and the airplane engine cover are your main flight instruments.
Look at the instrument panel only once in a while.

While the mouse is in yoke\index{yoke!mouse yoke mode} control mode ($+$ pointer), do not move it close to the FlightGear window edge.
Once the mouse leaves the window, it stops controlling the aircraft, often at the worse possible moment!
If you wish to use the mouse outside of the window, first go back to standard mouse mode by pressing \key{Tab} twice.

You can also control the yoke using the four \key{keyboard arrow} keys or the keypad \key{8}, \key{2}, \key{4} and \key{6} keys.
While initially this may seem easier than the mouse, you cannot make the very fine adjustments
required for accurate flying, so it is much better to persevere with the mouse.

You may hear beeping sounds while flying around the airport.
These are landing aid signals\index{landing!aid signals}.
Don't worry about them for the moment.

You will know that you have mastered this when you can make the aircraft climb steadily in the air.
The next step is to learn to keep the aircraft at a constant altitude, or to make it ascend or descend slowly and under your control.

Keeping the aircraft at a constant altitude involves observing the altimeter and making small changes with the mouse forwards or
backwards to stop the aircraft ascending or descending respectively.

\index{altimeter} The altimeter instrument is at the middle top of the instrument panel.
The long needle shows hundreds of feet, the short needle shows thousands of feet.
The altimeter below shows an altitude of 800 feet, approximately 245 meters.
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/altimeter}
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/altimeter-hotspot}
}
\medskip

As you ascend or descend the altimeter will change accordingly, turning anti-clockwise as you descend, and clockwise as you gain height.
If you see the altimeter ``unwinding'' you will be able to tell that you are losing height and move the mouse backwards
slightly to raise the nose.
After a while you will notice that when flying level the nose of the aircraft is always in the same position relative to the horizon.
This is the aircraft attitude for level flight.
By putting the nose in that same position, you will achieve almost level flight without having to reference the instruments.
From there you can fine-tune your altitude.

Beware: an altimeter does not automatically show the absolute altitude above sea level\index{altitude!absolute}.
You must adjust for the local air pressure.
The little black knob on the lower left side of the altimeter\index{altimeter!tuning} allows you to adjust the altimeter.
Start \FlightGear{} and stay on the ground.
Click (in normal mouse mode) inside the black knob and drag the mouse left or right.
A drag toward the left makes the altimeter decrease in indicated altitude.
Dragging toward the right will result in an increase in indicated altitude.
Use that little knob to set the altimeter to the field elevation of your airport.
The principle is that you use the knob when you know your present altitude.
If you know you are at 1,100 feet altitude, tune in 1,100 feet on the altimeter.
Type \key{Ctrl}-\key{c} to see the knob highlighted so that you understand the allowable click region.

To make settings the altimeter easier, airports advertise their altitude in various ways.
They may provide a radio service (called ATIS in the USA) to broadcast the current air pressure at sea level.
This is expressed in inches of mercury.
The altimeter contains a small scale inside which is calibrated in this way.
You can set your altimeter using this scale.
Alternatively, if you are on the ground and know the altitude of the airport, you can simply adjust your altimeter until it
displays the correct altitude.

Note that there is an important difference between ``altitude above mean sea level'' and ``altitude above ground level''.
If you fly near Mount Everest at an altitude of 24,000 feet above mean sea level (MSL), your altitude above ground level
(AGL) will be much less.
Knowing the altitude of the ground around you is obviously useful.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Basic Turns}
\label{sec:InFlightTurning}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/turn-coordinator}\index{turn coordinator}
\end{wrapfigure}
While, if you had enough fuel, you could return to the same airport by flying straight head for thousands of miles,
being able to change direction will make your flying more enjoyable and useful.

Once you are able to fly more or less straight, it is time to learn to turn.
The principle is simple:
\begin{itemize}
  \item When the airplane is banked to the left, it turns to the left.
  \item When banked to the right, it turns to the right.
\end{itemize}

To turn, you do not need high levels of bank.
20\textdegree{} is more than enough for a safe and steady turn.
Besides, passengers find excessive bank angles very disheartening.
They don't like it!
\medskip

\noindent\fbox{The turn coordinator does NOT represent bank angle.}
\medskip

\begin{Sidebar}
  For the inquisitive pilot, you would be interested to know that the bank angle required to establish a 3\textdegree{}, standard
  rate turn varies with True Airspeed (TAS).
  You could calculate an approximation with the formula:
  
  \[ angle \approx \frac{TAS (knots)}{10} + 7 \]
  \smallskip
  \centerline{
    \begin{tabular}{| c | c | c |}
      \hline
      TAS (knots) & formula & angle \\
      \hline
      80  & 8 + 7 & 15\textdegree{} \\
      100 & 10 + 7 & 17\textdegree{} \\
      120 & 12 + 7 & 19\textdegree{} \\
      \hline
    \end{tabular}
  }
\end{Sidebar}
The turn coordinator represents Rate of Turn.
The standard rate of turn is defined as 3\textdegree{} of travel per second.
Why is this important? Frankly, because it can save your life!
If you even find yourself suddenly in poor visibility, your smart reaction is to turn around 180\textdegree{}.
In poor visibility, how are you suppose to know when you have turned halfway around?
Hopefully, the standard rate of turn is now making sense to you.
If you perform a standard rate turn, covering 3\textdegree{} of the turn every second, then a 180\textdegree{} turn will
complete in one minute.
After two minutes, you would have turned in a full circle and returned back to where you started your turn.
This explains the ``2 minute'' placard you often see printed on the face of the instrument.

With this knowledge, let us explore how to properly utilize the turn coordinator instrument.
As you bank the aircraft to the right, notice how the airplane depicted on the instrument lowers its right wing.
Likewise, banking the aircraft to the left is duplicated on the face of the turn coordinator.
When the wingtip aligns with the tickmark along the rim, at that point nuetralize the control yoke to maintain that angle.
Glance quickly at the clock and roll out of the turn one minute later.
I know you were curious as to why airplanes had clocks.

Try the following: keep the airplane banked in a standard rate turn for a few minutes and keep your eyes outside the aircraft.
You will see the same ground features appear again and again, every 120 seconds.
This demostrates that you need 120 seconds to make a 360\textdegree{} turn (or 60 seconds for a 180\textdegree{} turn.)
This is particularly useful when navigating.
Whatever speed the airplane is flying, if you hold a bank at the standard rate you always need 60 seconds to make a
180\textdegree{} turn in the Cessna 172P (or any other aircraft).

So, by banking the airplane to the left or to the right, you make it turn to the left or to the right.
Keeping the airplane level, in relation to the horizon, establishes you into a straight and level flight path.
\medskip

The little ball, at the bottom of the turn indicator, shows the sideways forces acting upon the aircraft.
In real life you would feel these forces as you turn.
However, it is not possible to simulate these, so you must simply keep an ``eye on the ball''.
Think of the ball as representing the position of the tail of the airplane.
If you turn neatly (a.k.a. a coordinated turn), the ball will remain centered.
If the ball is pushed, say rightwards, this means that you the pilot too are pushed rightwards.
During a coordinated turn, even a strong turn, the plane occupants do not endure a sideways force.
They are only pushed a little harder into their seats by the centrifugal force.
To maintain coordination, simply ``step on the ball''.
When you see the ball deflected toward the right, push on the right pedal to return the ball to the center.
Likewise, the left pedal will return the ball to the center when deflected to the left.

By experimenting you will notice you can make much steeper turns by banking the airplane to high angles and pulling back on the yoke.
Turns at over 60\textdegree{} bank angle are the realm of aerobatics and military flying, and dangerous to aircraft such as the Cessna.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Taxiing on the ground}
\label{sec:TaxiTurning}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/tach}
\end{wrapfigure}
While \FlightGear{} is able to start you off conveniently lined up on the runway, you may be wondering how to
get your aircraft from its hangar, along the taxiways, to the runway.
This is taxiing.

The picture to the right shows the tachometer\index{tachometer} instrument.
It displays how fast the engine is turning in hundreds of revolutions per minute (RPM).
\medskip

Tap the \key{PageUp} key a few times, until the tachometer is showing 1,000 RPM (as shown above).
If required tap the \key{PageDown} key to decrease the engine speed.

At roughly 1,000 RPM, the airplane will move forward on the runway, but it will not accelerate and take off.

\index{brakes!right wheel [.] (dot)}
Tap the ``\key{.}'' key (\key{Shift-;} on Azerty keyboards).
The airplane will make a sharp turn to the right.
If you keep the ``\key{.}'' key down the airplane will halt.
When you tap the ``\key{.}'' key, you are activating the brake on the right wheel of the airplane.

\index{brakes!left wheel [,] (colon)}
To activate the brake on the left wheel, use the ``\key{,}'' key.

\index{brakes}
The ``\key{,}'' and ``\key{.}'' keys simulate two brake pedals located at your feet on a real airplane.
Using the throttle and the brake pedals you can control the speed of the aircraft and cause it to turn on the ground.

The brakes can be very useful when taxiing slowly on the ramp and taxiways.
You can also steer the nose-wheel of the aircraft.
In a real airplane this is done by pushing the rudder pedals with your feet.
You push with your feet on the side you want to turn toward.
If you don't have real rudder pedals, there are two ways to control the virtual rudder pedals:

\begin{itemize}
  \item Using the keypad \key{0} and \key{Enter} keys.\index{rudder!keyboard control}
        If you type the keypad \key{Enter} key say seven times, you will see the airplane firmly turns to the right and
        stays turning that way.
        Type the keypad \key{0} key seven times to get the airplane back rolling (almost) straight.
  \item Using the mouse.
        While the mouse is in yoke control mode ($+$ pointer), if you hold the left mouse button down, the mouse
        controls the rudder pedals instead of the yoke.
        The rudder pedals are connected to both the rudder \index{mouse!rudder control}
        \index{rudder!mouse control} and nose-wheel.
        This method is much more precise.
\end{itemize}

Start the simulator, Type \key{v} or \key{V} to view the airplane from the outside and keep \key{x} down a couple of
seconds to zoom in on the airplane.
Look at the front wheel and keep keypad \key{0} down.
Then keep keypad \key{Enter} down.
See the front wheel turn.
Press \key{Tab} to get in yoke control mode ($+$ pointer).
Keep the left mouse button down to get in rudder control mode and move the mouse to the left and to the right.
Note that the rudder, that big vertical control surface at the rear of the plane, moves together with the front wheel.

I tend to control the rudder pedals using the mouse while the front wheel is on the ground and use the keypad \key{0} and \key{Enter}
keys once it has lifted off.
In other words: I keep the left mouse button down while the front wheel is on the ground.
This allows for a precise and easy rudder control on the ground.
Then I simply release the left mouse button once the front wheel lifts off the surface.

\subsection{Airspeed}

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/airspeed}
\end{wrapfigure}
Just like driving a car, it is good to know how fast you are traveling.
The aviation equivalent of a speedometer is the airspeed indicator (ASI), calibrated to nautical miles per hour (knots).
\medskip

\begin{Sidebar}
  One nautical mile is the distance covered by 1-arc-minute of latitude.\\(1852 meters.)\\\\
  One knot is equivilent to the speed required to travel one nautical mile per hour.\\(60 knots = 60 nm / hour.)
\end{Sidebar}

A knot\index{speed!units!knot [nautical mile per hour]} is 1.852 kilometer/hour.
So, if you want to have a rough idea of your speed in flight expressed in km/h, multiply the knots displayed by 2.
A knot is 1.15115 miles per hour, so very roughly, 1 knot is 1 mph.
Note that some aircraft ASIs (in particular the Piper J3 Cub) display mph instead of knots.

The airspeed indicator displays the speed of the aircraft compared to the surrounding air, not the speed compared to the
ground like a car speedometer does.
If the plane is halted on the ground and there is a 10 knot wind blowing from straight ahead, the airspeed indicator will
display 10 knots airspeed, although the plane will not be moving relative to the ground.

When the airplane rolls over the runway at more than 40 knots, you must prevent the front wheel from touching the ground.
The nosewheel is not designed for high speeds and in real life would shimmy and wear out.

During take off, once over 40 knots you can make the front wheel leave the ground by pulling back gently on the control yoke.
Don't turn sharply at high speed on the ground.
Doing so may cause the aircraft to tip over.

The picture below shows the front wheel slightly lifted.
Don't overdo this.
Keep the airplane's white nose cover well below the horizon.
You just need to lift the plane's nose very slightly.

Question: if the front wheel no longer touches the runway, how do you steer the airplane? Answer: still using the rudder pedals.
As mentioned above, the rudder pedals are linked to both the nose-wheel and the tail rudder, that
big vertical moving part at the tail of the plane:

\begin{center}
  \includegraphics[width=\textwidth]{img/basic_tutorial/rotation}
\end{center}

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/rudder}
\end{wrapfigure}
At airspeeds above 40 knots, the rudder has enought airflow over it to steer the airplane.

Note the front wheel and the tail rudder don't make the airplane turn at exactly the same rate.
So when the rudder takes over the front wheel, you must adapt the rudder pedals angle.
That means fast typing keypad \key{0} and keypad \key{Enter} (or hold the left mouse button down and
tightly control the rudder with the mouse.)

Once you've become familiar with the nose-wheel and rudder, you can use these new controls to keep the airplane
straight on the runway during take-off.

Say the airplane is heading too much to the right.
You type keypad \key{0} a few times to make it turn back to the left.
Do not wait till the aircraft has straightened up completely.
Type keypad \key{Enter} before the aircraft reaches the direction you wish to travel.
Otherwise you will find that you will over-correct and have to turn back again.
If you use the mouse, such corrections are much easier and more precise.

To summarise: two methods exist to steer the airplane on the ground: the differential brakes on the main wheels and the rudder pedals.
This control redundancy is very common in aviation. If one method fails, you still have another method available to perform the task.

You may be wondering why the aircraft drifts to the left when it rolls on the ground, forcing you to compensate with a little
push on the right rudder pedal?
The main reason is engine torque.
As the propeller rotates clockwise, an opposite force is rolling the aircraft counter-clockwise.
This transfers a force onto the left main gear and tire.
This force results is a slight increase in drag and a slightly smaller tire radius.
A secondary reason is the flow of air produced by the propeller.
It blows along the airplane body, but also corkscrews around the airplane fuselage.
The upper part of that slight vortex pushes the vertical tail to the right.
This causes the front of the aircraft to yaw a bit to the left.

You can center all yoke and rudder controls by typing \key{5} on the keypad.
This is a good preflight precaution.
Sometimes it can ``save your life'' in flight if you find yourself with controls all over the place!

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Advanced Turns}
\label{sec:Turning}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

As with turning on the ground, there are two methods of turning in the air.
You can use the wing ailerons (steered by the yoke/mouse) as described above or you can use the tail rudder
(steered by the rudder pedals / the keypad keys /\key{0} and \key{Enter}.

Why two ways?
Partially for redundancy, but mainly because they are complementary.
The main effect of the rudder is yaw (rotation around the vertical axis), while the main effect of the ailerons is roll
(rotation around the longitudonal axis.)

\begin{itemize}
  \item When flying close to the ground, it is better not to bank the airplane in order to turn.
        The rudder is used more instead.
        Acting on the rudder pedals allows you to turn the airplane without excessive banking.
  \item When the plane is just above the runway, the two side wheels need to be at the same height above the runway for landing.
        That means the wings must be level with the horizon.
        The plane is not allowed to bank.
        You keep the plane wings level with the horizon by using the yoke/mouse/ailerons.
        Note this does not need to be perfect.
        A bank of a few degrees is harmless.
	\item In flight, especially at high speed, the rudder is an in-efficient way to turn the aircraft:
	      \begin{itemize}
		      \item It causes the airplane to present its flank to the airstream, increasing drag.
		      \item The airplane turns very slowly.
		      \item You will lack control while turning.
		      \item At high flight speed the centrifugal force will be disturbing or even dangerous.
	      \end{itemize}
	      Using the yoke/mouse/ailerons allows for efficient, fast, reliable and comfortable turns.
  \item The rudder can be vital when the wings are stalled.
        Indeed, during a stall the wing ailerons become less effective or even useless.
	      (Note that some airplanes can go in a very dangerous stall if you overdo the rudder control at low speed.)
\end{itemize}

When you turn in flight, using the ailerons, you still need the rudder a little bit.
You add a little bit of rudder.
This allows you to compensate for the adverse yaw created when you roll using the ailerons.
In a real aircraft, you can feel this sideways motion.
In the simulator, you can check this visually on the turn coordinator.
In the picture below the little ball is pushed rightwards during a strong turn to the right using the ailerons.
That means you the pilot endure a rightwards force too.
You can compensate this by pushing the right rudder pedal (type the keypad \key{Enter} key a few times.)
In normal flight you should use the rudder to keep the little ball centered.

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/turn-coordinator-2}
\end{wrapfigure}

So, in normal flight use the ailerons to turn, while close to the ground at low speed use the rudder.
However, one method never completely cancels out the other.
You still need the rudder at high altitudes and speeds.
Reciprocally you have to use the ailerons a little bit when close to the ground, to keep the wings level with the horizon.

Even when taxiing, you should use the ailerons.
Otherwise, strong winds can blow the aircraft onto its side.
To counteract this, your should turn the ailerons into the wind.
This raises the aileron in the wind, helping to keep the wing down.

You should avoid making quick and agressive movements of the rudder.
On the ground at high speed this can make the airplane turn too sharply.
In flight at low speed it can cause a very dangerous type of stall.
In flight at high speed it can cause all kinds of aerodynamic and physical discomfort.
Instead, make gentle movements of the rudder.

I recommend you practise turning with the rudder in flight.
Fly at a low speed of about 70 knots.
Try to keep the altitude stable by increasing and decreasing the engine power.
Use the rudder to turn towards a ground feature and maintain a heading, then turn the aircraft towards a new heading.
See how the plane yaws.
Learn to anticipate rudder control.
Don't try to make steep turns.
Use the yoke/ailerons to keep the wings level constantly.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{A Bit of Wieheisterology}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Wieheisterology comes from the German phrase ``Wie hei\ss t Er'' -- ``What's that name''.
This section is about gauges, switches and controls of the aircraft.
While in the simulator you can take off and land a basic airplane with just the engine throttle and the yoke, but you will
need all the controls to perform securely and efficiently.

\subsection{Engine control}
\label{sec:EngineControl}

An airplane engine is designed for simplicity, reliability and efficiency.
Rather than use advanced electronic ignition and fuel injection systems found in modern cars, they instead use older
technology that doesn't rely on electrical power.
That way, the plane can still fly even if it suffers complete electrical failure.

\subsection*{Magneto}\index{magneto}

On the bottom left, below the instrument panel you will find the magneto switch and engine starter:

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/mags}
\end{wrapfigure}

To see the switch, either type \key{P} to get the schematic instrument panel or type \key{Shift-x} to
zoom out (\key{x} or \key{Ctrl-x} to zoom back in.)

You can move the switch with the \key{\{} and \key{\}} keys (use the \key{Alt Gr} key on Azerty keyboards.)

You are probably aware that the fuel inside a car engine is ignited by electric sparks.
Modern car engines use electronic ignition.
An airplane engine uses a more old-fashioned (but more reliable) magneto ignition instead.
For redundancy, it contains two such magnetos: the ``left'' one and the ``right'' one.
When you change the magneto switch on OFF, both magnetos are switched off and the engine will not run.
With the magneto switch on L you are using the left magneto.
On R you are using the right magneto.
On BOTH you use both.
In flight you will use BOTH.

Given that you use both magnetos in flight, why have the switch?
The reason is that during your preflight checks you will verify that each of the magnetos is working correctly.
To do this, increase the RPM to about 1500 then switch the magneto switch to L and observe the tachometer.
You should observe a slight drop in RPM.
If the engine cuts out, the left magneto is broken.
If you do not see an RPM drop, then the switch may be faulty, as both magnetos are still switched on.
You can then perform the same test on the right magneto.
Of course, in the simulator, the magnetos are unlikely to fail!

Should one of the two magnetos fail in flight, the other one will keep the engine running.
The failure of one magneto is rare, the failure of both simultaneously is almost unheard of.

You may have typed \key{\{} to shut the engine down.
To start the engine again after doing so, type \key{\}} three times in order to put the magneto switch on BOTH.
Then use the starter motor by pressing the \key{s} for a few seconds, till the engine is started.

You can also turn the magneto switch and start the engine by clicking left and right of the switch in normal mouse mod.
Type \key{Ctrl-c} to see the two click sides highlighted by yellow rectangles.

If you turn the switch to OFF, the engine noise stops.
If you quickly turn the switch back to L, the engine starts again as the propeller is still turning.
If you wait for the propeller to stop, placing the switch on L, R or BOTH won't start the engine.
(Once the engine is halted, always place the magneto switch to OFF.)

\subsection*{Throttle}\index{throttle lever}

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/throt-mix}
\end{wrapfigure}

You already know that you increase the engine power by pushing that throttle rod in (\key{PageUp} key).
You decrease the power by pulling the control out (\key{PageDown} key).
You can also click left and right of the lever (middle mouse button for quicker moves, \key{Ctrl-c} to
highlight the left and right halves.)

What does ``increase the power'' actually mean?
Does it mean you increase the amount of fuel delivered to the engine?
Yes, but this is not enough to fully understand what you are doing.
You need to be aware that the engine is also fed with a huge amount of air.
The engine's cylinders burn an \Index{mixture} of fuel and air.
Fuel alone wouldn't burn.
Only a mixture of fuel and air can detonate and move the engine pistons.
So when you push the throttle in, you increase both the fuel and the air fed to the engine.

\subsection*{Mixture}\index{mixture}

The amount of air compared to the amount of fuel is critical.
The proportion of the two has to be tuned closely.
This is the purpose of the mixture lever.
The picture below displays the mixture lever, pulled out far too much.

When the \index{mixture!lever} mixture lever is fully pushed in, you feed the engine with an lots of fuel and little air.
This is known as a ``rich'' mixture.
When the lever is pulled out completely, there is an excess of air, known as a ``lean'' mixture.
The correct position to produce maximum power is in between these two extremes, usually quite close to fully pushed in.

When you start the engine and when you take off, you need a fuel-rich mixture.
That means the mixture lever should be pushed in.
A fuel-rich mixture allows the engine to start easily.
It also makes the engine a little more reliable.
The drawback is that a part of the fuel is not burned inside the engine.
It is simply wasted and pushed out the exhaust.
This makes the engine more polluting, it decreases the energy the engine can deliver and it slowly degrades the
engine by causing deposits of residues inside the cylinders.
\index{mixture!optimisation}

Once in normal flight, you have to pull the mixture lever a little, to get a more optimal mixture.
Check this out by doing the following.
Start the simulator.
Put the parking brakes on with key B (that is \key{Shift-b}).
Push the throttle in to its maximum.
The engine RPM should now be close to the maximum.
Slowly pull on the mixture lever (using the mouse in normal pointer mode.)
You will see the RPM increases a little.
You get more power, without increasing the fuel intake.
You waste no fuel and it pollutes less.
If you continue to pull the mixture lever, the RPM will decrease back away, because now there is too much air.
The excess of air slows the explosions down inside the cylinders and decreases the explosion temperature, hence the
thermodynamic yield decreases.
You have to tune in the optimal mixture.
For thermodynamic reasons, the best mixture isn't exactly at maximum power -
it is better for the engine to be running very slight richer or leaner than maximum power.
This also avoids the possibility of the fuel detonating explosively damaging the engine.
You can find the maximum power point by the fact you get the highest RPM.
(Another method is to check the engine exhaust temperature.
Roughly, this is the point at which you get the highest temperature.)

The mixture control allows you to burn less fuel for the same speed and distance, and therefore fly farther and pollute less.
However, if you mis-manage it, it can cause serious problems.
Suppose you go flying at high altitude and pull out the mixture lever accordingly.
At high altitude there is less oxygen available so the correct mixture will be quite lean - i.e. with little fuel being used.
Then you descend back in order to land.
If you forget to push the mixture lever in as you descend, the fuel/air mixture will become far too lean and the
engine will simply halt.

When landing, you have to tune back in a mixture that is a little too rich in fuel.
This means pushing the mixture lever in.
That way the engine becomes a little more reliable and will be better adapted to a decrease in altitude.

I wrote above that placing the magneto on OFF is not the right way to stop the engine.
The right method is to pull the mixture lever\index{engine!shut down}.
First pull the throttle out completely, to get the engine to minimum power and fuel consumption.
Then pull the mixture lever, till the engine stops because the mixture contains too much air.
This ensures the engine doesn't get choked by waste fuel residues.
Finally, turn the magneto switch to OFF to ensure the engine won't start again accidentally.

An important warning: you may think the RPM indicator reflects the engine power.
Wrong.
Two things make the RPM increase: the engine power and the airplane speed.
To check this, fly to a given altitude then pull the engine power to minimum.
Try out diving to the ground then rising back to altitude.
You will see the RPM varies significantly as does your airspeed.
It rises while diving and decreases while climbing.

One pitfall of this is when you intend to tune the engine power in for landing.
Suppose you're descending towards the airport, flying fast.
You know the ideal RPM for landing is around 1,900 RPM.
So you pull the throttle till you get 1,900 RPM.
You think you tuned in the appropriate RPM.
You think you shouldn't bother any more about it.
But when you level off, the plane's speed starts to decrease, along with the RPM.
A few minutes later, you get the low flight speed you wanted.
You don't see the RPM is now far too slow.
You will either lose altitude or stall.
Or both.
Be cautious with the throttle and with the RPM indicator.
Either pull on the throttle more steadily or be mentally prepared to push it back in quickly.

\subsection{Wings and speed}
\label{sec:WingsAndForce}

Say you are flying with full engine power.
Dropping the nose a little makes you lose altitude and raising the nose a little makes you gain altitude.
You may think this is quite straightforward.
The plane travels in the direction it is heading; the direction the propeller is heading.
This is not the best way to think about it.
This model would be fine for a rocket, but not for an airplane.
A rocket is lifted by its engine, while a plane is lifted by its wings.
That's a huge difference.

Get a big rigid square of cardboard, hold it horizontally in your hand with your arm stretched out and make it do fast
horizontal movements while rotating your torso.
When the cardboard moves flat through the air, it experiences no lift force.
If you twist your arm slightly to give the cardboard a slight upward angle, you will feel it tends to lift in the air.
There is an upward force acting on the cardboard.
That's the way a wing holds a plane in the air.
The wings have a slight upward angle and lift the airplane.
The more angle you give the cardboard, the more lift force.
(Till you give it too steep an angle.
Then you will rather feel a brake force.
The cardboard is ``stalling'' (see below.).)
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/lift}
}
\medskip

\begin{itemize}
  \item When you pull the yoke, the airplane's nose rises up.
        Hence the wings travel through the air at a steeper angle.
        Hence the lift force on the wings is stronger.
        Hence the plane rises in the air.
  \item When you push the yoke, the airplane's nose dives.
        Hence the wings travel through the air with less angle.
        Hence the lift force on the wings decreases.
        Hence the plane descends.
\end{itemize}

What matters is the angle the wings travel through the air.
This is the angle of attack.

I wrote above that when the wings travel through the air with no angle of attack, they don't produce lift.
This is false.
It would be true if the wings were a flat plate like the cardboard.
But they aren't.
The wings are a slightly curved airfoil.
This makes them create lift even when traveling through the air at no angle of attack.
Actually, even with a little negative angle of attack they still create a lift force.
At high speed the airplane flies with the wings slightly angled towards the ground!
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/airfoil}
}
\medskip

The angle at which the wings travel through the air matters.
Something else matters too: the speed.
Take the cardboard again in your hand.
Hold it with a given slight angle and don't change that angle.
Move it at different speeds through the air.
The faster you move the cardboard, the more upward force it experiences.
\begin{itemize}
	\item When you increase the engine power, the plane increases speed, the lift force on the wings increases and the plane gains altitude.
	\item When you decrease the engine power, the plane decreases speed, the lift force on the wings decreases and the plane loses altitude.
\end{itemize}

To make things a little more complicated:
when rising in the air, the airplane tends to lose speed. When descending, it tends to gain speed.

That's all a matter of compromises.
If you want to fly at a constant altitude and at a given speed, you will have to tune both the engine power and the yoke/elevator
(or better: the trim (see below)), till you get what you want.
If you want to descend yet keep the same speed, you have to push the yoke a little and decrease the engine power.
And so on.
You constantly have to tune both the engine power and the yoke.
However, during a normal flight you can simplify this by simply choosing a comfortable engine power level then relying on the yoke and
trim for altitude.

A very interesting exercise you can perform with the simulator is to fly straight with full engine power.
Get maximum speed while keeping in horizontal flight.
Then decrease the engine power to minimum.
Pull steadily on the yoke to keep the plane at constant altitude.
The plane slows down steadily, meanwhile you have pull more and more on the yoke to stay level.
Since the speed decreases the lift from the wing will decrease, but you compensate the loss of speed by increasing the wing
angle of attack.
This proves the plane does not necessarily travel in the direction its nose is heading.
In this experiment we make the nose rise in order to stay at constant altitude.
Once the plane is flying very slowly, and the nose is very high, you may hear a siren yell.
That's the stall warning (see below.)
This indicates that the angle of attack is too high for the airfoil to produce lift.
The wings are no longer producing lift and the plane quickly loses altitude.
The only way to correct this is push the yoke forwards to reduce the angle of attach, making the nose drop, then apply
full power to gain speed and finally bring the yoke carefully back to level flight.

Question: is it better to control the airplane's speed and altitude with the yoke or with the throttle?
Answer: it depends on what exactly you intent to do and on the situation you are in.
In normal flight, as said above, you tend to set a comfortable engine power level, forget about it and rely on the yoke and trim.
During take off and landing the procedures are quite strict about the use of yoke and throttle.
You do the opposite: control the speed with the yoke and trim, control the altitude and descent speed with the engine throttle.
This will be discussed further below.

\subsection{The flaps} \index{flaps}
\label{sec:Flaps}

The flaps are situated at the rear of the wings, either side of the aircraft fuselage.
You deploy the flaps and retract them back in by using the \index{flaps!control lever}flaps control lever:
\medskip

\centerline{
  \includegraphics[width=0.6\textwidth]{img/basic_tutorial/flaps}
  \includegraphics[width=0.315\textwidth]{img/basic_tutorial/flaps-ctl}
}
\medskip

You can either click on it with the mouse or use the \key{[} and \key{]} keys.
Key \key{[} to retract the flaps one step, \key{]} to deploy them one step at a time.
Type \key{v} to view the plane from the outside and try out \key{[} and \key{]}.
(On the schematic instrument panel the flaps lever is located at the lower right.)

In the Cessna 172P. there are four \index{flaps!steps}flaps settings:
\begin{itemize}
	\item 0\textdegree{} - for normal flight and normal take off.
  \item 10\textdegree{} - for short field take off, when you want to gain altitude while flying slowly.
        Or during the first stange of an approach to land.
	\item 20\textdegree{} - to slow the aircraft and lose altitude quickly, for example
	      when descending towards the runway to land.
	\item 30\textdegree{} - To lose altitude even more quickly.
\end{itemize}

The flaps are somewhat delicate.
Do not deploy the first step of flaps above 110 knots.
Do not deploy the second or third stage of flaps above 85 knots.

The flaps create large amounts of drag on the aircraft and brake the plane at high speed.
This is one more reason not to forget to pull the flaps back in once you fly above 85 or 110 knots.

To check the flaps position visually, either use the mouse view mode to look at the back of the wing,
or type \key{Shift}-\key{right arrow} to shift the view to the right and then quickly \key{Shift}-\key{up
arrow} to get back to front view.

Flaps increase wing lift by altering the shape of the airfoil.
The wing lifts more at a given speed with the first stage of flaps set.
Hence you will get in the air a little sooner during take off.
It also has the effect to make the plane fly with a lower nose attitude.
This is useful as it provides a better view of the runway when taking off or landing.

The flaps also increase drag on the aircraft.
The second and third stage of flaps produce much more drag than lift, so they are used to brake the plane.
This is particularly useful when landing, because the airplane glides very well.
If you cut down the engine power completely, the plane will descend, yet but too slowly.
You need to deploy two or three flaps steps in order to brake and really descend towards the ground.

The fact that the flaps brake during landing makes you need more engine power during the landing.
This can seem odd. Why not simply throttle the engine down to minimum and use less flaps steps?
The answer is that it is better to have a strongly braking plane and lots of engine power,
as the plane reacts faster to your commands.
Should the engine fail, then just retract flaps as needed and glide to the runway.

\index{side-slip}
What can you do if you have full flaps extended and need to increase your rate of descent further?
Slowly push the rudder pedals on one side.
This will make the plane present its flank to the air stream and brake.
Compensate the turning by using the ailerons (yoke).
This is known as side-slipping, and is a very effective way to lose height progressively as it is easy to stop at any point.

\subsection{The stall}\index{stall}
\label{sec:Stall}

An aircraft relies on the smooth flow of air over the surface of the wing to produce lift.
However, if the wing is at too high an angle of attack, this flow is broken, and the wing no-longer produces lift.
With no lift, the aircraft cannot fly, and quickly drops back to earth.
This is known as a stall.

A stall is an emergency situation, whatever the While it can happen at any speed, it commonly occurs in slow flight.
A given aircraft has a specific stall speed, at which no angle of attack can produce enough lift.
You should always keep your aircraft well above the stall speed.
To help, aircraft are equipped with stall sirens that sound when the angle of attack is approached.

If you encounter a stall, the remedial action is to immediately drop the nose, and apply full power, bringing the nose
level when flying speed has been attained again.
However, doing so will cause the aircraft to lose altitude, which you may not have to spare when landing or taking off!

\index{spin}A spin occurs when one wing stalls before the other, which can occur in a steep turn at low speed.
As one wing is still flying, the aircraft turns around the stalled wing, spinning tighter and tighter.
To get out of a spin, you need to apply rudder to straighten out the spin into a normal stall, then recover as above.

Aircraft like the Cessna 172 and Piper Cub, have benign stalls, and are unlikely to enter a spin. High performance jets,
such as the F16 have much more agressive stalls, and can easily enter a spin.

To practise this in the simulator, do the following:
\begin{itemize}
	\item Fly at constant altitude and attitude.
	\item Reduce engine power, raising the nose to avoid entering a descent.
	\item Continue to reduce power until the stall begins.
	\item Try to control the plane while it stalls and descends to the ground.
  \item Keep the yoke pulled to the maximum and the plane in a steady attitude, the wings parallel with the horizon.
        Try to change direction.
	\item Recover by lowering the nose, applying full power, and correcting the attitude once flying speed has been regained.
\end{itemize}

You can also experiment with stalls with different flap settings, and high speed stalls by making abrupt attitude changes.

Experiment with different aircraft.
Compared with the Cessna 172 the Cessna Citation jet, stalls much more agressively and with little warning.

\newpage
\subsection{The trim}\index{trim}
\label{sec:Trim}
\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/trim}
\end{wrapfigure}
The trim is the dark big vertical wheel with gray dots located at the middle below the instrument panel:

On \FlightGear{}, the keys \key{Home} and \key{End} adjust the trim.
\key{Home} rolls the wheel upwards while the \key{End} rolls the wheel downwards.
You can also click on the upper or lower half of the trim wheel.

In first approximation, the trim does the same as the yoke: it acts on the elevator.
Turning the trim wheel downwards is the same as pulling on the yoke.
Yet there is a key difference between the trim and the yoke.
The trim remains in position after you make a change, while the yoke only continues to affect the elevator while you apply pressure and
returns the elevator to neutral when you release it.

During cruise flight, the required elevator position to keep the aircraft at constand altitude will not be completely neutral -
it will vary depending on the air outside the aircraft, the current fuel level, and the payload.
Obviously, holding the yoke continually to retain a constant attitude would quickly become tiring.
By using the trim to ``trim out'' the elevator force required for cruise flight, the yoke can be kept neutral.

During take off the trim should be neutral.
Otherwise you may find that it either refuses to take-off with the normal level of yoke control, or takes off too quickly.

During landing, try to get the yoke / mouse / elevator towards neutral position by tuning the trim.
This makes making small adjustments to your attitude and position easier.
On the Cessna 172p this means trim on neutral.
On the Cherokee Warrior II this means the trim a little ``pulled''.

The trim wheel movement is much slower than the yoke, allowing for delicate changes in trim. Be patient.

\subsection{What direction am I flying?}
\label{sec:Kierunek}

Knowing the direction you are going is obviously a good idea.
There are three basic ways to determine the direction you are flying:

\begin{itemize}
  \item Look through the windows.
        If you are flying regularly from the same airport, you will learn to recognize the ground features such as roads, hills,
        bridges, cities, forests.
        In a simulator, you only have a narrow view of the virtual outside world.
        Several ways exist to allow you to pan your virtual head inside the airplane:
	      \begin{itemize}
		      \item Use \key{Shift} and the four arrow keys to look to the front, rear, left and right.
		      \item Use \key{Shift} and the keypad keys to look in the four directions mentioned above and in four diagonal directions
		            in-between.
		      \item Hold down the right mouse button in normal or yoke mode and move the  mouse to change the view direction.
          \item Use the mouse in view mode (\key{Tab}, $\leftrightarrow$).
                This allows you to look in every direction, including up and down.
                Click the left mouse button to bring the view back to straight ahead.
	      \end{itemize}
  \item The magnetic compass.
        This is located above the instrument panel.
        The compass is simple, but is affected by the acceleration of the aircraft, and magnetic abnormalities on the ground.
        Also, the compass points towards magnetic north rather than true north.
        This deviation varies depending on your location.
  \item The directional gyro (picture below) or ``heading indicator''.
        The gyro is powered by a vacuum system.
        The gyro is set to match the magnetic compass, and is not affected by magnetic issues, or aircraft movement.
        However, due to gyroscopic precession and friction in the instrument, over time it drifts and must be reset by
        reference to the magnetic compass on ocassion.
        To reset the HI, during cruise flight, use the black knob on the bottom left of the instrument
	      (normal mouse pointer mode, click left or right half of the knob, middle mouse button to move faster,
	      \key{Ctrl}-\key{c} to highlight halves.)
	      (The red knob, bottom right, is used to tell the autopilot what direction
	      you wish to fly (\textcolor{red}{\button{HDG}} = ``heading''.)
\end{itemize}
\medskip

\centerline{
  \includegraphics[height=6.0cm]{img/basic_tutorial/compass}
  \includegraphics[height=6.0cm]{img/basic_tutorial/DG}
}
\medskip

\subsection{A look around the panel}

Finally, let's have a look at the instrument panel, combining the instruments described above with some new ones.

\subsubsection{The six-pack}

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/attitude-indicator}
\end{wrapfigure}
Let us start with the most important instruments any simulator pilot must know, these are known as the ``holy six'' or the ``six-pack''.
In the center of the instrument panel (Fig.\,5), in the upper row, you will find the \Index{artificial horizon}
(\Index{attitude indicator}) displaying\Index{pitch} and \Index{bank} of your plane.
It has pitch marks as well as bank marks at 10, 20, 30, 60, and 90 degrees.

Left of the artificial horizon, you'll see the \Index{airspeed indicator}.
Not only does it provide a speed indication in knots but also several arcs showing characteristic \Index{velocity rages} you
have to consider.
At first, there is a green arc indicating the normal operating range of speed with the \Index{flaps} fully retracted.
The white arc indicates the range of speed with flaps in action.
The yellow arc shows a range which should only be used in smooth air.
The upper end of it has a red radial indicating the speed you must never exceeded, unless you want to break up the
plane in mid-flights\ldots

Below the airspeed indicator you can find the \Index{turn indicator}.
The airplane in the middle indicates the roll of your plane.
If the left or right wing of the plane is aligned with one of the marks, this would indicate a standard turn,
i.e. a turn of 360 degrees in exactly two minutes.

Below the plane, still in the turn indicator, is the \Index{inclinometer}.
It indicates whether the \Index{rudder} and \Index{aileron}s are co-ordinated.
During turns, you always have to operate \Index{aileron} and \Index{rudder} in such a way that the ball in the tube
remains centered; otherwise the plane is skidding. A simple rule says:
``Step on the ball'', i.e. step onto the left rudder pedal when the ball is on the left-hand side.
\medskip

If you don't have pedals or lack the experience to handle the proper ratio between aileron and rudder automatically,
you can start \FlightGear{} with the option:

\texttt{-$ $-enable-auto-coordination}\index{auto coordination}

To the right-hand side of the artificial horizon you will find the
\Index{altimeter} showing the height above sea level (not ground!) in hundreds of feet.
Below the altimeter is the \Index{vertical speed indicator} indicating the rate of climbing or sinking of your plane in
hundreds of feet per minute.
While you may find it more convenient to use than the altimeter in certain cases, keep in mind that its display usually
has a certain time-lag.

Further below the vertical speed indicator is the propellor tachometer, or RPM (rotations per minute)
indicator\index{RPM indicator}, which displays the rotations per minute in hundreds.
The green arc marks the optimum region for cruise flight.

The group of the main instruments further includes the \Index{gyro compass} being situated below the artificial horizon.
Besides this one, there is a \Index{magnetic compass} sitting on top of the panel.

Four of these gauges being arranged in the from of a ``T'' are of special importance:
The air speed indicator, the artificial horizon, the altimeter, and the compass should be scanned regularly during flight.

\subsubsection{Supplementary Instruments}

Beside the six-pack, there are several supplementary instruments.
To the very left you will find the \Index{clock}, obviously being an important tool for instance for determining turn rates.
Below the clock there are several smaller gauges displaying the technical state of your engine.
Certainly the most important of them is the \Index{fuel indicator} - as any pilot should know.

The \Index{ignition switch} is situated in the lower left corner of the panel (cf. Fig.\,4).
It has five positions: ``OFF'', ``L'', ``R'', ``BOTH'', and ``START''.
The first one is obvious.
``L'' and ``R'' do not refer to two engines (as the Cessna 172 only has one) but the two magnetos, providing
redundancy in the case of a failure.
The two switch positions can be used for test puposes during preflight.
During normal flight the switch should point on ``BOTH''.
The extreme right position is for \index{starting the engine} using a battery-powered \Index{starter} (operated with the ``s'' key).

The handle below the yoke is the parking brake.
In the vertical position, the parking brake is ON. The parking brake is operated with the ``B'' key.

\subsubsection{Radios}

The right hand side of the panel is occupied by the \Index{radio stack}.
Here you find two \Index{VOR} receivers (NAV),\index{NAV} an \Index{NDB} receiver
(\Index{ADF}) and two \Index{communication radio}s (COMM1/2)
\index{COMM1}\index{COMM2} as well as the autopilot.

The \Index{communication radio} is used for communication with \Index{air traffic facilities};
it is just a usual radio transceiver working in a special frequency range.
The frequency is displayed in the LEDs.
Usually there are two \Index{COM transceiver}s;
this way you can dial in the frequency of the next controller to contact while still being in contact with the previous one.

The COM radio can be used to listen to the current weather conditions at an airport, known as ATIS.
To do this, simply dial in the ATIS frequency of the relevant airport.
You can find this by selecting \texttt{ATC/AI->Frequencies} from the menu, and selecting the 4-letter ICAO code of a nearby airport.

Each COM radio has two frequencies configured - an `active' frequency which the pilot is transmitting and receiving on,
and a `standby' frequency which may be changed.
In this way, you can continue to listen on one frequency while tuning another one.

You can change the radio frequency using the mouse.
For this purpose, click left/right to the circular knob below the corresponding number.
The corresponding switch left to this knob can be used for toggling between the active/standby frequency.

Use of the autopilot and radio navigation equipement is covered in later tutorials.
For the moment you can ignore these radio instruments as long as you are strictly flying according to \Index{VFR} (\Index{visual
flight rules}).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Let's Fly}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

By now you will be able to keep on runway while taking off by using the rudder and you're able to fly straight, descend, climb
and make gentle turns.
This section will describe a slightly more realistic approach to taking off and landing, and introduce some of the more subtle
concepts you should be aware of.

\subsection{A realistic take off}
\label{sec:Start}

The following general rules apply during a normal take-off:
\begin{itemize}
	\item The nose-wheel should be lifted from the runway at approximately 40 knots.
  \item Immediately after take-off, you should accelerate to 70 knots, to stay well above stall speed,
        in case of a gust of wind, or engine failure.
	\item Don't fly much above 75 knots to ensure you gain height as quickly as possible.
  \item Follow the runway heading until at 500 feet.
        This way, if you suffer an engine failure, you can easily land back on the runway you left.
	\item Don't over-fly buildings until at least 1,000 ft.
	\item Close to the ground, turns should be gentle and well coordinated using the rudder.
\end{itemize}

So, you need to take off and rise in the air at a steady speed of around 75 knots.
However, when you raise the nose slightly at 40 knots, the aircraft will probably take-off at around 55 knots.
To accelerate quickly to 75 knots, lower the nose slightly immediately on take-off, then raise it once 75 knots has been achieved.
You are using the yoke to control the speed of the aircraft.

Putting this all together with what you have learned previously, a normal take-off using the mouse will consist of the following:

\begin{enumerate}
  \item Adjust the altimeter to the correct altitude, based on the airport altitude.
        For reference, KSFO is at sea level - 0ft.
	\item Check aileron and elevator are neutral by observing the yoke position.
	\item Change the mouse to control mode by pressing \key{Tab}.
	\item Hold the left mouse button down to control the rudder.
	\item Apply full power (hold \key{PgUp} until the throttle is fully in.)
	\item As the aircraft accelerates down the runway, keep it in the center by making small adjustments using the mouse.
  \item As 40kts is reached, release the left mouse button, and pull back slightly to raise the nose-wheel.
        You are now controlling the yoke with the mouse.
	\item The aircraft will fly off the runway at approximately 55 knots.
	\item Lower the nose slightly to accelerate to 70 knots.
	\item Keep alignment with the runway.
  \item Use the yoke to keep the ASI at 70 knots as you climb.
        If the airspeed is dropping, lower the nose.
        If the airspeed is increasing, raise the nose slightly.
	\item Once you reach 500 feet, turn to your required heading, staying away from buildings until you are over 1,000ft.
\end{enumerate}

\subsection{Landing}\index{landing}
\label{sec:Ladowanie}

The rules for landing are almost identical to that of take-off, but in reverse order:
\begin{itemize}
	\item Close to the ground, turns should be gentle and well coordinated using the rudder.
	\item Stay above 500ft until on final approach to the runway.
	\item Approach the runway at approximately 70 knots.
	\item Touch down on the two main wheels at 55kts.
	\item Let the nosewheel touch down at 40kts.
\end{itemize}

Landings are much easier if you have an aiming point picked out on the runway.
By observing the aiming point, you can easily tell if you are descending too fast or too slowly.
If the aiming point appears to move upwards, you are descending too fast.

Obviously, you need to be lined up with the runway.
That means your flight direction has to match the middle line of the runway (drawing (a) below).
In order to arrive at this, don't aim at the start of the runway (b).
Rather aim at a fictitious point well in front of the runway (c).
And begin to turn gently towards the runway well before you reach that fictitious point (d).
Note the turns and bankings you make for these flight corrections are often very soft.
You wouldn't even notice them on the turn coordinator.
This is one example where you better rely on the outside horizon line than on the inside flight instruments.
\medskip

\centerline{
  \includegraphics[width=0.65\textwidth]{img/basic_tutorial/runway-alignment}
}
\medskip

A straight in landing using the mouse would consist of the following:
\begin{enumerate}
  \item 1,500ft above the airport, and a couple of miles out, an in-line with the runway, reduce power to approximately 1500rpm.
        This will slow you down somewhat and start a gradual descent.
  \item Once below 115 knots, apply one step of flaps (\key{]}).
        This will increase lift, but also slow you down.
	\item Re-trim the aircraft so you continue to descend.
  \item At around 1,000 feet, apply another step of flaps (\key{]}).
        This increase drag significantly, but also improve the view over the nose.
  \item Tune the speed using the elevator and trim: push the yoke if you are flying below 70 knots, pull the yoke if you are
        flying above 70 knots.
        If using a joystick, use the trim to relieve any pressure on the elevator.
  \item Tune the altitude using the engine throttle.
        Add power if you are descending too fast, reduce power if you are too high.
        It is much easier to work out if you are too high or too low by observing the numbers on the runway.
	      If they are moving up the screen, you are descending too fast - increase power.
	      If they are moving down, you are too high and need to reduce power.
	\item Make minor adjustments to heading to keep aligned with the runway.
  \item At about 500ft, apply the final step of flaps. (\key{]}).
        This increase drag significantly, so be prepared to increase power to keep your descent constant.
  \item When you are just above the runway, reduce power to idle, and use the yoke to gently pull back the aircraft to horizontal.
        This is the ``round-out'' and should result in the aircraft flying level with the runway a couple of feet above the surface.
        Performing the round-out at the correct height is a difficult task to master.
        To make it easier, observe the horizon rather than getting fixated on the aiming point.
  \item Keep the wings level using small inputs with the yoke.
        We want both wheels to touch down at the same time.
  \item Continue pulling back on the yoke.
        The main wheels should touch down at about 55 knots.
        This is the ``flare''.
	\item As you touch down, be ready to use the rudder to keep the aircraft straight (keypad \key{0} and keypad \key{Enter})
	\item Once you are below 40 knots, lower the nose-wheel to the ground.
	\item Hold down the left mouse button to control the nosewheel / rudder using the mouse.
	\item Once below 30 knots, use the brakes \key{b} to slow the aircraft further.
\end{enumerate}

Once the plane is halted or at very low speed, you can release the \key{b} key and add a little engine power to taxi to the
parking or hangar.
\medskip

\centerline{
  \includegraphics[width=\textwidth]{img/basic_tutorial/landing}
}
\medskip

\subsection{Engine Shutdown}\index{shutdown}

To shut the engine down:
\begin{itemize}
	\item Set the parking brake, type \key{B}.
	\item Engine throttle to minimum (hold \key{PageDown} down for a while.)
  \item Pull the mixture lever to halt the engine
        (mouse in normal pointer mode, click on the left of the red mixture lever to pull it out.)
	\item Rotate the magneto switch to OFF (a few hits on \key{\{}).
\end{itemize}

\subsection{Aborted Landing}\index{abort}

You must be mentally prepared to abort landing any time the landing does not look good, or due to external factors such as:
\begin{itemize}
	\item an order from the control tower.
	\item incorrect speed or landing angle when there is insufficient time to correct it.
	\item a strong gust blow of wind.
	\item birds flying over the runway.
\end{itemize}

To abort the landing, apply full power (hold \key{PgUp}), raise the nose to climb, and once you are climbing, retract the flaps (key{[}).

Landing is much harder than taking off.
Landing on a large runway, such as KSFO (San Francisco) is much easier than smaller runways such as KHAF
(Half Moon Bay, about 10 miles to the south west of KSFO.)

To practise landings, use the command line below in a terminal window to start the simulator in flight and heading for the runway.
The airplane is placed 5 miles ahead of the runway, at an altitude of \textbf{1500} feet and a speed of about 120 knots.

\command{fgfs -$ $-offset-distance=5 -$ $-altitude=1500

\hspace{3em}-$ $-vc=120 -$ $-timeofday=noon}

Approaching to land at 65 knots instead of 70 knots allows to use a much shorter runway length.
However, this requires better control, particularly as it is much closer to the stall speed.
It is quite different from landing at 70 knots.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Dealing with the Wind}
\label{sec:Fwsw}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Consider a hot air balloon.
Think of it as being in the middle of a gigantic cube of air.
The cube of air may move at high speed compared to the ground, but the balloon itself is completely static in the middle of the cube.
Whatever the wind speed, persons aboard a hot air balloon experience not a breath of wind.

In the same way, an aircraft flies in the middle of a gigantic cube of air and flies relative to that air mass.
The motion of the cube of air relative to the ground has no effect on the aircraft.

You, the pilot, on the contrary, are interested in the speed of the surrounding air compared to the ground.
It can make you drift to the left or to the right.
It can make you arrive at your destination much later or much sooner than planed.

When the wind blows in the same direction as you fly, the speed of the wind adds itself to the airspeed of the plane.
Hence you move faster compared to the ground.
You will arrive earlier at your destination.

When the wind blows in the opposite direction (towards the nose of the plane), the speed of the wind subtracts itself from the airspeed
of the plane.
Hence you move slower compared to the ground.
You will arrive later at your destination and have more time to enjoy the landscape.

The two cases above are quite simple.
More complex is when the wind blows towards the side of the airplane.
Consider the diagram below.

\begin{itemize}
  \item On picture (a) there is no wind.
        The pilot wants to reach the green hill situated to the North.
        He heads for the hill, towards the North, and reaches the hill after a while.
        When there is no wind, you just head towards your destination and everything's fine.
  \item On picture (b), the pilot keeps heading to the North.
        Yet there is wind blowing from the left; from the West.
        The airplane drifts to the right and misses the hill.
  \item On picture (c), the pilot keeps heading towards the hill.
        This time he will arrive at the hill.
        Yet the plane flies a curved path.
        This makes the pilot lose time to get to the hill.
        Such a curved path is awful when you need to make precise navigation.
  \item Picture (d) shows the optimal way to get to the hill.
        The plane is directed to the left of the hill, slightly towards the West and the wind.
	      That way it compensates for the wind and remains on a straight path towards the hill.
\end{itemize}
\medskip

\centerline{
  \includegraphics[width=0.65\textwidth]{img/basic_tutorial/wind-force}
}
\medskip

How much to the left or to the right of the object must you head?
At what angle?
Serious pilots use geometry and trigonometric computations to calculate the correct angle.
You need no computations at all to fly roughly straight.
The trick is to choose an aiming point in the direction you wish to fly, then observe how it moves.
You will become aware if you are drifting leftwards or rightwards.
Then let your instinct slowly head the plane to the right or to the left to compensate the obvious drift.
To begin with, you may need to think about what you are doing.
Very soon this will become automatic, just like when you learned to fly straight.
You will no more keep the plane headed towards the object.
You will rather keep it flying towards the object.

The faster the flight airspeed compared to the wind speed, the less correction you will need.

\subsection{Crosswind Take Off}
\label{sec:Swsw}

Taking off when the wind is coming from the side is tricky.
Airport designers avoid this by placing runways so that they face into the prevailing wind.
Often airports have multiple runways, placed such that there will be a runway facing straight into wind as much of the time as possible.

Taking off with a wind blowing straight towards the nose of the aircraft makes life easier as it is the speed of the wing
relative to the air that causes lift.
When there is no wind, the aircraft must accelerate to 55 knots to take off.
However, if there is a 10 knot head-wind, the aircraft has an airspeed of 10 knots standing still and only has to accelerate to
45 knots relative to the ground to take off.
This shortens take-off distances.

Just as a headwind shortens take-off, a tail-wind increases take-off length.
Anything more than a knot or two makes a huge difference to take-off distance.
As (most) runways can be flown from either end, you can easily take off from the other end of the runway and benefit from the headwing.

The main way to know the wind direction and speed is to go to the control tower or ask the control tower by radio.
A necessary and complementary tool are the windsocks\index{windsock} at both ends of the runway.
They show the wind direction and speed.
The longer and the stiffer the windsock, the more wind there is.
The windsock on the picture below shows an airspeed of 5 knots:

\begin{center}
\includegraphics[width=\textwidth]{img/basic_tutorial/windsock-5kts}
\end{center}


Unfortunately, sometimes there isn't a runway facing the wind, and you have to take off when the wind is blowing from the side.

The technique is as for a normal take-off with two changes:
\begin{itemize}
  \item During the take-off roll, the aircraft will try to ``weather-cock'' into wind.
        You must react by using the rudder to keep the aircraft running straight.
        You will have to apply the rudder at quite a strong angle to stay aligned with the runway.
        You will need to keep applying rudder throughout the take-off.
	\item As you take off, the aircraft will react to the rudder and try to turn.
        You will need to correct for this using the ailerons.
        Once the aircraft is in the air, you can reduce the rudder pressure and aileron, then correct for the wind, to keep
        aligned with the runway as described above.
\end{itemize}

\subsection{Crosswind Landing}
\label{sec:Lwsw}

Landing in a crosswind is very similar to the take-off:
\begin{itemize}
	\item Stay aligned with the runway by compensating for the crosswind.
  \item As you begin to round-out, use the yoke to straighten the aircraft so it is pointed down the runway.
        Apply rudder to stop the aircraft turning.
  \item The aircraft will land on one wheel first.
        Use the rudder to keep the aircraft pointed straight down the runway as the other wheel touches down.
\end{itemize}

The technique described here is the \weblong{http://en.wikipedia.org/wiki/Slip_landing}{slip landing}.
Another crosswind landing technique is the \weblong{http://en.wikipedia.org/wiki/Crab_landing}{crab landing}.

\subsection{Taxiing in the Wind}
\label{sec:Twsw}

Under 10 knots wind the Cessna 172p seems not to need particular precautions when taxiing.
Yet any sudden increase in wind speed can tilt it and tumble it over.
So best apply the recommendations whenever there is wind.

To train taxiing on the ground when there is wind, configure the simulator for a strong wind, like 20 knots.
Such a wind can tilt the plane and blow it away tumbling any moment.
One single error during taxiing and the plane is lost.

Main rule is you must \emph{push the yoke towards the wind}.
This deserves some physical explanation:
\begin{itemize}
  \item When the wind is blowing from 12 o'clock, this is quite logical.
        The yoke is pushed (towards 12 o'clock) and the elevator makes the tail rise a little.
        That's the most stable position to avoid the plane be tilted by the wind.
  \item When the wind comes from 10 o'clock, pushing the yoke towards 10 o'clock means that the elevator is almost neutral,
        while the left aileron is upward and the right aileron is downward.
        This pushes the left wing down and lifts the right wing.
        Again, that's the most stable position to avoid the plane be tilted by the wind.
  \item When the wind blows from 8 o'clock, you would think you should invert the position of the ailerons, to keep the left
        wing being pushed down.
        Hence you should push the yoke to 4 o'clock.
        Wrong! Keep pushing the yoke to 8 o'clock.
        The reason is the downward position of the aileron on the right wing makes it act like a slat.
        This increases the lift on the right wing and this is all we want.
        Symmetrically, the upward position of the left aileron decreases the lift of the left wing.
  \item When the wind comes from the rear, from 6 o'clock, the yoke is pulled (toward 6 o'clock).
        The upward position of the elevator tends to make the tail be pushed down.
        Once again this is the best.
        Strong wind can push the tail against the ground.
        This is impressive but the tail is conceived to withstand this.
\end{itemize}

If you want to move towards the wind, you will need more engine power.
When the wind blows from the rear you may need no engine power at all.
Always keep the engine power to the minimum needed.

Especially when turning, move very slowly.
Make little changes at a time.
Take your time and closely survey the yoke angle.
Constantly keep it pushed towards the wind.
Constantly try to reduce the engine power.
Keep in mind using the brakes too firmly may shortly tilt the plane at an angle that allows the wind to tilt it and blow it away.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{The autopilot}\index{autopilot}
\label{sec:Autopilot}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{wrapfigure}{r}{0.35\textwidth}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/autopilot}
  \includegraphics[width=0.35\textwidth]{img/basic_tutorial/autopilot-2}
\end{wrapfigure}
An autopilot is not an ``intelligent'' pilot.
It just takes over simple tasks for the pilot.
You still are the pilot aboard and have to keep aware of everything.
Be prepared to shut the autopilot down as they often go wrong, both in real life, and in the simulator.

The autopilot is mounted to the right of the yoke.

Switch it on by pressing the \button{AP} button.
The autopilot then controls the \index{autopilot!modes!roll control mode}roll of the aircraft.
It keeps the wings level with the horizon.
This is displayed in the picture below by the ``\textcolor{orange}{\button{ROL}}'' marking.
To switch the autopilot off press \button{AP} again.

\index{autopilot!modes!heading mode}
If you press the \button{HDG} button the autopilot will try to keep the plane flying towards the direction tuned on the
directional gyro by the red marking (see section \ref{sec:Kierunek}.)
``\textcolor{orange}{\button{HDG}}'' stands for ``heading''.
Press again on the \button{HDG} button to get back to roll control mode (or \button{AP} to switch the autopilot off).

The buttons \button{ALT}, \button{UP} and \button{DN} are used to tell the autopilot either to control the vertical
\index{autopilot!modes!vertical speed mode}speed \textcolor{orange}{\button{VS}} or the altitude \textcolor{orange}{\button{ALT}}.
For more advanced use of the autopilot, see the reference document for the autopilot modelled in the Cessna 172:
\weblong{https://dealer.bendixking.com/servlet/com.honeywell.aes.utility.PDFDownLoadServlet?FileName=/TechPubs/repository/006-18034-0000_3.pdf}{Bendix King website}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{What Next?}
\label{sec:Poslowie}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

This tutorial has introduced you to the basics fo flight in the Cessna 172.
From here you can explore the many features that \FlightGear{} has to offer.

Once you have mastered the content of this tutorial, you may want to look at the other tutorials in this Manual,
covering flying to other airports, flying using instruments when clouds obscure the ground, and flying helicopters.

This tutorial has skipped over a number of topics that a real-life pilot would have to consider:
\begin{itemize}
	\item How to follow real checklists.
	\item How to make emergency landing on very short fields, after and engine failure.
	\item How to navigate with regard to the laws of the air, charts, laws, radio beacons and weather conditions.
	\item How to create a flight plan and fly it accurately.
	\item How to place people, fuel and baggage in an airplane to get a correct center of gravity.
	\item How to deal with the control tower and with other airplanes.
	\item How to deal with several fuel tanks and their systems.
	\item How to deal with the failure of every possible part of the plane.
\end{itemize}

This tutorial has also not covered features of more advanced aircraft, including:
\begin{itemize}
  \item retractable landing gear
  \item variable pitch propellers
  \item multiple engines
  \item jet engines.
\end{itemize}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Thanks}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

I wish to thank:
\begin{itemize}
	\item Benno Schulenberg who corrected lots of mistakes in my English in this tutorial.
	\item Albert Frank who gave me key data on piloting and corrected technical errors.
	\item Vassilii Khachaturov who learned me new things about \FlightGear{}.
	\item Roy Vegard Ovesen for pointing me to the official Autopilot Pilots Guide.
	\item Dene Maxwell for his solution for problems under Windows Me.
	\item Mark Akermann and Paul Surgeon for their remarks.
	\item Michael ``Sam van der Mac'' Maciejewski who made the translation in Polish and converted the tutorial for use in the manual.
	\item The \FlightGear{} mailing list users for their hearty welcome.
	\item \weblong{http://www.4p8.com}{4p8} webmaster my friend Fr\`{e}d\`{e}ric Cloth for
	      the web space used by this tutorial.
\end{itemize}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Flying Other Aircraft}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

I cross-checked all the data about the Cessna 172p, a pilot friend verified I did not write too much rubbish and I made numerous
virtual test flights.
This section contains less reliable data about other airplanes based on my experience in the simulator.
You may find it useful as an introduction to those airplanes but bear in mind my only goal was to make flights that seem OK and
acquire basic knowledge.

\subsection{How to land the Cherokee Warrior II}
\label{sec:Cherokee}

The Cherokee Warrior II has some advantages upon the Cessna 172p.
Thanks to its low wings it is far less sensitive to crosswind.
Fully extended flaps are provide more braking and allow it to land on a much shorter distance.

Take off is the same as for the Cessna 172p in \FlightGear{}.
In real life their take off checklists are not exactly the same.

You have to get used to some minor differences of the Cherokee Warrior II for the landing:

\begin{itemize}
  \item During the steady horizontal flight before landing, the trim must be pulled a little below neutral in order to get the
        yoke around neutral.
  \item The optimal tachometer RPM during landing is at a lower RPM than the tachometer green zone.
        Roughly, keep the needle vertical.
  \item Only put use two steps of flaps during landing.
        Don't decrease the engine throttle too much.
  \item If you remain at two flaps deployed during landing, the round-out and flare will be similar to the Cessna 172p.
        However, using the third set of flaps will slow the aircraft down dramatically.
        It will very quickly touch the runway then come to a near halt.
        Be prepared to lower the front wheel very soon.
	      (It is possible to use the third flaps step during the descent towards the runway, instead of tuning the engine power down.
	      Oscillating between two steps and three steps allows to aim the runway start.
	      Yet keep two flaps steps and tune the engine seems easier.
        An interesting stunt is to fly stable till nearly above the runway start, then tune the engine to minimum and deploy three
        flaps steps.
	      The plane almost falls to the runway.
	      It's impressive but it works.)
\end{itemize}

In real life, an advantage of the Cessna 172p upon the Cherokee Warrior II is the fuel reservoirs of the Cessna are located in the
wings close above the center of the plane and higher than the engine.
What's more an automatic system switches between the reservoirs.
That means you almost don't have to bother for the way the fuel gets to the engine in flight.
On the contrary, on the Cherokee Warrior II the reservoirs are located separately, on both wings and lower than the engine.
That means you have to constantly switch between the two reservoirs in flight.
Should one reservoir become much lighter than the other, this would destabilize the airplane.
The fact the reservoirs are lower than the engine means you have to control the fuel pumps and the backup fuel pumps.

Some links:
\begin{itemize}
    \item \web{http://en.wikipedia.org/wiki/Piper\_Cherokee}
    \item \web{http://freechecklists.net/Resources/Piper/PA-28-151+Warrior/}
\end{itemize}

\subsection{How to take off and land the Piper J3 Cub}
\label{sec:PiperJ3}

The Piper J3 Cub is a very different airplane from the Cessna 172p and the Cherokee Warrior II.
The Cessna 172p and the Cherokee Warrior II are nose-wheel airplanes, while the Piper J3 Cub is a tail wheel airplane.
Take off and landing with tail wheel airplanes is more difficult.
You have to tightly use the rudder pedals when rolling over the runway.
The yoke often needs to be pulled backwards to the maximum.
The Piper J3 Cub is a good introduction to tail-wheel aircraft and it is quite easy to take off and land provided you follow an
appropriate procedure.
Stall speed seems to be a little below 40 mph (the airspeed indicator is in mph) (about 27 knots).
Take-off is below 50 mph.

My take off procedure for the Piper Cub is to fully pull the yoke backwards then throttle the engine to maximum.
Once the front wheels clearly rises from the ground, gently push the yoke back to neutral, towards a normal flight close above the runway.
Let the plane accelerate to 50 mph.
Then pull the yoke to keep a little more than 50 mph while rising in the air.

The landing procedure is quite different to that of 172, as the aircraft is very light, and has no flaps.
\begin{enumerate}
  \item Fly at say 500 feet constant altitude and "exactly" 52 mph speed towards the runway.
        Let the engine cover eat up the runway start.
        The engine cover will hide the runway completely.
        To see where the runway is, push the yoke/mouse very shortly then stabilize again in normal flight.
  \item Once the runway start matches with the set of instruments (if you could see through the instrument panel), reduce the
        throttle to a near minimum and begin the dive towards the runway start.
        Keep 52 mph using the yoke.
        Add some throttle if you are going to miss the runway edge.
	      (Keep in mind just a little wind is enough to change things a lot for the Piper J3 Cub.)
  \item Make the rounding and pull the throttle to minimum.
        Do not pull steadily on the yoke.
        Instead let the wheels roll on the runway immediately.
  \item Once the wheels roll on the runway, \emph{push} firmly on the yoke, to its maximum.
        This rises the tail in the air.
	      You would think the propeller will hit the runway or the airplane will tilt over and be damaged.
	      But everything's fine.
	      The wings are at a strong negative angle and this brakes the plane.
	      (Don't push the yoke this way on other airplanes, even if their shape seems close to that of the Piper J3 Cub.
	      Most of them will tumble forwards.)
  \item The yoke being pushed in to its maximum, push the left mouse button and keep it pushed to go in rudder control mode.
        Keep the plane more or less centered on the runway.
        This is quite uneasy.
        One tip is to stop aiming the rudder to say the left already when the plane just starts to turn to the left.
	\item Once the speed is really low (and the rudder control stabilized), you will see the tail begins to sink to the ground.
	      Release the left mouse button to go back to yoke control.
	      Pull the yoke backwards completely, to the other extreme.
	      The tail now touches the ground and the nose is high up.
	      Now you can use the wheel brakes (\key{b}).
	      (If you use the brakes too early, the plane nose will hit the ground.)
\end{enumerate}

The take off procedure mentioned above is symmetrical to the first landing procedure.
There exists a second take off procedure, symmetrical to the second landing procedure.
Yet I don't succeed it properly so I won't write about it.

\subsection{How to take off and land a jet}
\label{sec:Jet}

Take off on a jet is easy but you must have fast reflexes.
My favorite jet on FlightGear is the A-4 Skyhawk.
You get it with the \command{--aircraft=a4-uiuc} parameter on Linux, provided it is installed.

This is the ``calm'' procedure to take off:

\begin{itemize}
  \item Ask for a red and full \index{HUD (Head-Up Display)}\index{HUD (Head-Up Display!full mode)} HUD by typing \key{h} two times.
        The engine throttle indicator is the leftmost on the HUD.
  \item The airspeed indicator is the one labeled "KIAS" on the upper left side of the instrument panel.
        You can also use the airspeed indicator on the HUD, of course.
	\item Tune in $1\over2$ engine power.
  \item Keep the yoke pulled in $1\over2$ of its total way (picture below: the red arrow on the right side of the vertical line in the
        middle of the picture.)

        \begin{center}
		      \includegraphics[width=0.35\textwidth]{img/basic_tutorial/hud-yoke-up}
	      \end{center}

  \item It is not mandatory to use the rudder to keep on the runway.
        The airplane will take off before it drifts off the runway.
        (For sure it is better and more ``secure'' to keep in the middle of the runway.
        But using the rudder can make things hectic for a beginner.)
  \item Once above about 160 knots, the plane rises its nose in the air.
        Immediately push the yoke back to neutral or almost and stabilize at 200 knots airspeed (which makes a fair climb angle)
        (I've no idea whether 200 knots is the right climb speed for a real A-4. What's more I suppose one should rather use the
        AOA (see below.).)
	\item Retract the landing gear using key \key{g}.
  \item Either maintain $1\over2$ engine power and a speed of 200 knots to get above the clouds, or reduce the engine power to
        less than $1\over4$ and fly normally.
        (Off course you can ``fly normally'' with full engine power. Great fun.)
\end{itemize}

The ``nervous'' take off procedure is the same but you push in full engine power.
The plane takes off quickly and you need to settle a very steep climb angle to keep 200 knots.
Best retract the landing gear immediately.

You don't land a jet the same way you land a little propeller airplane.
My way to land the A-4, inspired by some texts I found on the Web, is this:
\begin{itemize}
    \item Really far from the runway, keep below 2,000 feet and get the speed below 200 knots.
          Then lower the landing gear (key \key{G}) and I deploy full flaps (all three steps, by hitting \key{]} three times.)
    \item Keep a steady altitude of about 1,000 feet and a speed of ``exactly'' 150 knots.
          Use the mouse / yoke / elevator to tune the altitude and the engine throttle to tune the speed.
          (The opposite from the Cessna.)
    \item Try to align with the runway.
    \item When do you know the dive towards the runway must begin? For this you need the \index{HUD (Head-Up Display)} HUD;
          the full default HUD with lots of features.
          Look at the picture below.
          When you see the ``distance'' between the red ``0'' lines and the runway start is 25\% the distance between the
          red ``0'' lines and the red ``$-10$'' dotted line, it is time to dive, aiming at the runway start.
          (In the picture below, that ``distance'' is 64\%, far too much to start a landing.)

\begin{center}
\includegraphics[width=\textwidth]{img/basic_tutorial/HUD-landing}
\end{center}

Let's explain this.
The two horizontal lines labeled ``0'' show the horizon line.
Rather they show where the horizon would be if the Earth was flat.
When your eyes aim at those ``0'' lines, you are looking horizontally.
Look at the dotted red lines labeled ``$-10$''.
A feature on the ground situated there is situated 10\textdegree{} below the ideal horizon.
In other words: when you look to objects ``hidden'' by the lines labeled ``0'', you have to lower your eyes of 10\textdegree{}
to look at objects "hidden" by the dotted lines labeled ``$-10$''.
This implies, and it is very important, that a person in a rowboat, ``hidden'' by the dotted lines labeled ``$-10$'',
has to rise his eyes up 10\textdegree{} to look at your plane.
He sees you 10\textdegree{} above the horizon.
In the picture above, the start of the runway is situated at 64\% of the way towards the red ``-10'' dotted lines.
That means you have to lower your eyes of 6,4\textdegree{} to look at the runway start.
This also means that if you start now to descent towards the runway start, the descent path will be of 6,4\textdegree{} (too steep).
So, the \index{HUD (Head-Up Display)} HUD allows to measure precisely the angle of the descent path.
On a jet plane you need an angle of 2,5\textdegree{} (up to 3\textdegree{}), that is 25\% of -10\textdegree{} (up to 30\%).

\begin{center}
\includegraphics[width=0.5\textwidth]{img/basic_tutorial/glideslope}
\end{center}

\item Once descending towards the runway start, aim at it using the yoke/mouse.
      And keep 150 knots speed using the engine throttle lever.
\item Keep measuring the angle between the ideal horizon and the runway start.
      It must keep 2,5\textdegree{} (that is 25\% of 10\textdegree{}):
\begin{itemize}
  \item [$\circ$] If the angle increases above 2,5\textdegree{}, you are above the desired path and you must loose altitude faster.
        Both decrease the engine power and dive the nose a little.
  \item [$\circ$] If the angle decreases below 2,5\textdegree{}, you are under the desired path.
        I wouldn't say you should gain altitude, rather you should loose altitude less fast.
        Both add a little engine power and rise the nose a little.
\end{itemize}
\item Once very close to the runway start, do no rounding.
      Don't pull steadily on the yoke like you would for the Cessna 172p.
      Simply let the plane touch the ground immediately, at high speed.
      Let it smash on the runway, so to say.
      All three wheels almost together.
      Just throttle the engine down to minimum.
      (If you try to pull steadily on the yoke and hover over the runway while the plane nose rises steadily, on a F-16 you would
      scrape the plane rear and probably destroy it.)
\item Keep the key \key{b} down to brake and use the rudder to stay aligned with the runway.
      Make only very little tunings with the rudder, otherwise the plane will tumble on one of its sides.
\end{itemize}

The HUD in a real jet contains a symbol to show towards what the airplane is moving.
It is shown in the picture below.
When you are flying at constant altitude, that symbol is on the ideal horizon line.
Once you dive towards the runway start, you simply have to place that symbol on the runway start.
This is quite an easy and precise way to aim at the runway start.
(The diamond in the center of the FlightGear HUD sometimes can help but it does not have the same purpose.
It shows towards what the airplane nose is pointing.
For example is you descent towards the ground at low speed, the symbol would be somewhere on the ground while the FlightGear
diamond will be up in the sky.)
(By the way, the HUD on the virtual B-52 on FlightGear has that symbol.
It is great to use while landing.)

\begin{center}
	\includegraphics[width=0.25\textwidth]{img/basic_tutorial/aim-point}
\end{center}

Also, a real HUD shows a dotted line at -2,5\textdegree{}, to help find the correct descent path.
Simply keep that dotted line on the runway thresh-hold.

In additional to airspeed, military fast jet pilots rely on using the correct angle of attack during approach.
The Angle Of Attack (AoA) is the angle at which the wings are pitched against the relative airflow.
The advantage of keeping to an optimal AoA is that the optimal AoA for landing does not depend on the plane load, while the
optimal airspeed speed does.
By ensuring that the AoA is correct for every landing, you will land at the correct speed, whatever the plane load.

The Angle of Attack is displayed within the HUD, and/or as a set of three lights shown below.
When the upper $\vee$ is lit, your angle of attack (AoA) is too high and you need to pitch down.
When the lower  $\wedge$  is lit, your AoA is too low and you need to pitch up.
The center  $\bigcirc$  indicates your the AoA is OK.
Obviously, as you pitch up or down your airspeed and descent rate will change, so you will need to change your throttle
setting appropriately.
\medskip

\centerline{
  \includegraphics[width=0.5\textwidth]{img/basic_tutorial/f-14b-hud}
}
\medskip

The Cessna 172 and the A-4 Skyhawk are two extremes.
Most other airplanes are in-between these two extremes.
If you trained them both (and one or two tail wheel airplanes), you should be able to find out how to take off and land most
other airplanes.

160 knots seems an appropriate landing speed for the F-16 Falcon.
Also you need to throttle down the engine to minimum just before the plane should touch the runway.
Otherwise it will hover over the runway.
Don't bother for the flaps.
It seems they are deployed automatically with the landing gear.
(Read the section \ref{sec:Stall} about the stall.)

140 up to 150 knots and all 8 flaps steps deployed seem appropriate to land the virtual Boeing 737.
But don't trust me especially on that one.
I just made a few experiments and didn't search for serious data.
The landing speed varies a lot depending on the plane load, I suppose 140 knots is for a plane with no load.
The Boeing 737 seems to like a gentle rounding before the wheels touch the runway.
Start the rounding early.

In the take off procedure for the Cessna 172 and the A-4 Skyhawk I recommend you pull the yoke/mouse/elevator to $1\over2$ the total
way, from the start on.
This seems to be a bad practice on the Pilatus PC-7.
Keep the elevator neutral.
Let the plane accelerate and wait till the speed gets over 100 knots.
Then pull calmly on the yoke.
During landing, deploy full flaps once you start plunging to the runway but don't decrease the engine throttle.
Decrease it only when the hovering above the runway starts.
100 knots seems a good landing speed.

For the Cessna 310 too you better leave the elevator neutral during the acceleration on the runway.
The plane will raise its nose by its own provided you deployed one flaps step.
(If you keep the yoke pulled from the start on, the nose will rise sooner and you will get
\textcolor[cmyk]{0,0.25,1,0}{\textbf{y}}awful yaw problems.)

(Some virtual airplanes, like some big airliners or fast aircraft, need faster physical computations.
Then add the \command{--model-hz=480} parameter to the command line.
If the plane is difficult to control during landings, try this.)

The angle at which you land a Cessna 172p is far steeper than the narrow 2,5\textdegree{} for a jet.
Nevertheless you are allowed to land the Cessna at a narrow angle too.
(Provided the terrain around the runway allows for this, of course.)
If you have passengers who have ears problems with the variation of air pressure\ldots

\subsection{How to take off and land the P-51D Mustang}
\label{sec:P-51D}

Should you ever get a chance to pilot a \weblong{http://en.wikipedia.org/wiki/P-51_Mustang}{P-51 Mustang}, just say no.
It is quite dangerous to take off and land.
That's the kind of airplane you fly only when your country is in danger.
You need a lot of training.
Yet once in the air the P-51 Mustang seems no more dangerous to its pilot than other common military airplanes.
It is quite easy to pilot.

At low and medium altitude the P-51 wasn't better than the Spitfire and the Messerschmitts.
The big difference was at high altitude.
The P-51 kept efficient and maneuverable while enemy fighters were just capable to hang in the air.
This was an advantage at medium altitude too because the P-51 was able to plunge towards enemy airplanes from high altitude.
Another key difference was the P-51 is very streamlined.
Hence it was capable to fly much further than the Spitfire.
These two differences let the P-51 Mustang fulfill its purpose: escort Allied bombers all the way to their targets in Germany.
This allowed the bombings to be much more efficient and contributed to the defeat of the Nazis.

To get the P-51D Mustang on Linux use the \command{--aircraft=p51d} command line parameter.

To take off the P-51D Mustang in \FlightGear{}, deploy one flaps step, pull and keep the yoke completely backwards, push the
engine throttle to maximum and keep the left mouse button pressed to control the rudder and keep on the runway.
Once you reach exactly 100 mph, suddenly push the rudder 1/3 of its total way to the right.
Immediately release the left mouse button and push the yoke to rise the tail (don't push it too much, as the sooner the wheels leave
the ground the better.)
From now on, keep the left mouse button released.
Only make very short adjustments to the rudder.
Let the plane rise from the runway and get to altitude at a speed of say 150 mph.
Don't forget to retract the landing gear and the flaps.

Don't make too steep turns.
You would loose control on the plane and crash.

To land, deploy full flaps and lower the landing gear from the start on.
130 mph speed seems fine, up to 140 mph.
Make an approach from 1,000 feet altitude and a dive at a low angle, like for a jet.
Once over the runway, shut the engine down completely (key{\{}).
Don't hover over the runway.
Get the wheels rolling soon (like for a jet).
Hold the left mouse button down to steer the plane using the rudder.
Once the tail sinks in, briskly pull the yoke (left mouse button shortly released) to force the tail on the runway.
Go on steering the plane using the rudder.
Now the tail is firmly on the ground, use the brakes if you want.

\subsection{How to take off and land the B-52 Stratofortress}
\label{sec:B52}

The B-52F bomber implemented in \FlightGear{} is a success.
It is one of my favorite airplanes.
I'm sorry it was conceived to terrify me.
One single B-52 bomber can wipe out every main town of my country and rise a nightmare of sicknesses and children malformation for
centuries.
All B-52 bombers united can wipe out mankind and almost every kinds of plants and animals on Earth.

The differences between the virtual B-52F bomber and the Cessna 172p are these:
\begin{itemize}
    \item The B-52F starts with the flaps deployed and the parking brakes set.
    \item There are only two flaps steps: retracted and deployed.
          When deployed they are only meant to make the wings lift more, not to brake.
          If you want to brake, you need the spoilers.
          They deploy on the upper side of the wings.
          Use the key \key{k} to deploy the spoilers and the key \key{j} to retract them.
          There are seven steps of spoilers.
    \item The main landing gear of the Cessna 172p is composed of two wheels, one on each side of the airplane.
          In order for these wheels to leave and touch the ground altogether, you need to keep the wings parallel with the ground.
          The main landing gear of the B-52F is composed of a set of wheels at the front and a set of wheels at the rear.
          This implies that in order for these wheels to leave and touch the ground altogether, you need to keep the airplane body
          parallel with the ground.
\end{itemize}
This is my procedure to take off the virtual B-52F:
\begin{itemize}
    \item \emph{Push} the yoke  $1\over3$ of the total way.
    \item Push the engine throttle to maximum.
    \item Release the parking brakes (key \key{B}).
    \item Push down the left mouse button to control the rudder pedals and keep the airplane on the runway.
    \item The whole runway length is needed till the B-52F rises from the ground (KSFO).
    \item Once the B-52F leaves the ground, around 190 knots seems appropriate to get to altitude.
    \item Retract the flaps and the landing gear.
\end{itemize}

To land, the B-52F's HUD offers that great airplane-shaped symbol I talked about in the section about jets.
So you just have to put that symbol on the airplane threshold (a few pixels further seems optimal) and keep the runway
start 2,5\textdegree{} below the ideal horizon line.
130 up to 140 knots seems a good landing speed.
(Instead of the speed you can make use of the AOA indicator displayed on the schematic instrument panel (\key{P}).)
Simply keep the AOA at 3\textdegree{}. I
must confess I prefer to tune the speed rather than the AOA.)
If the plane gets to the runway at 130 up to 140 knots, simply ``let it smash'' on the runway.
Otherwise, if the speed is higher, make a rounding and a short hover.
The brakes seem to be very effective \key{b}).
They allow to stop the B-52F on roughly the same short runway length as the Cessna 172p.

Replays of the flights are a delight.
They allow to check the plane body left the runway and landed back parallel with it.
One of the points of view is situated inside the B-52F rear turret, which allows you to be your own passenger and to compare what
you see with what you experienced as a passenger in airliners.
The key \key{K} allows to visualize the airplane trajectory.

To cause an accident with the B-52 do this:
\begin{itemize}
    \item Make a steep turn with a very strong bank; the wings nearly perpendicular to the ground.
    \item Try to get the plane back level.
          It will obey but very slowly.
          You will get aware that the turn will go on for a while and that you will turn further than your intended flight direction.
    \item Do something that accelerates the stabilization on some airplanes:
          push the rudder to an extreme, opposite to the current turn.
          This will suddenly make the airplane drop from the sky.
\end{itemize}
\translatorEnd
